{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-111101",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-26T15:10:33.224480Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-26T15:35:51.401Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "packageName": "bandit",
          "packageURL": "pkg:hex/bandit",
          "product": "bandit",
          "repo": "https://github.com/mtrudel/bandit",
          "vendor": "mtrudel",
          "versions": [
            {
              "lessThan": "1.14.0",
              "status": "affected",
              "version": "0.1.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "packageName": "mtrudel/bandit",
          "packageURL": "pkg:github/mtrudel/bandit",
          "product": "bandit",
          "repo": "https://github.com/mtrudel/bandit",
          "vendor": "mtrudel",
          "versions": [
            {
              "lessThan": "220b9dfd27f9a21305be2afc75cbe585ddc24e7a",
              "status": "affected",
              "version": "7201270c34b90f6c9e15c0386c2bb802c0c72ab4",
              "versionType": "git"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "1.14.0",
                  "versionStartIncluding": "0.1.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ],
          "operator": "AND"
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "Peter Ullrich"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Mat Trudel"
        },
        {
          "lang": "en",
          "type": "analyst",
          "value": "Jonatan M\u00e4nnchen / EEF"
        }
      ],
      "dateAssigned": "2026-10-23T12:35:54.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eAllocation of Resources Without Limits or Throttling vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory and CPU via a request body made of many 1-byte chunks.\u003c/p\u003e\n\u003cp\u003eThe chunked reader in \u003ccode\u003elib/bandit/http1/socket.ex\u003c/code\u003e keeps every chunk as its own list cell and binary term until \u003ccode\u003eIO.iodata_to_binary/1\u003c/code\u003e joins them, and nothing limits the number of chunks. The \u003ccode\u003e:length\u003c/code\u003e option of \u003ccode\u003eread_body/2\u003c/code\u003e counts only data bytes, so tiny chunks cost far more memory than their payload: 48 MB of 1-byte chunks grew one handler process to about 500 MB and took about 6 s of CPU. The route does not need to read the body, because on keep-alive connections \u003ccode\u003eensure_completed/1\u003c/code\u003e drains unread bodies through the same reader.\u003c/p\u003e\n\u003cp\u003eThis issue affects bandit: from 0.1.0 before 1.14.0.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory and CPU via a request body made of many 1-byte chunks.\n\nThe chunked reader in `lib/bandit/http1/socket.ex` keeps every chunk as its own list cell and binary term until `IO.iodata_to_binary/1` joins them, and nothing limits the number of chunks. The `:length` option of `read_body/2` counts only data bytes, so tiny chunks cost far more memory than their payload: 48 MB of 1-byte chunks grew one handler process to about 500 MB and took about 6 s of CPU. The route does not need to read the body, because on keep-alive connections `ensure_completed/1` drains unread bodies through the same reader.\n\nThis issue affects bandit: from 0.1.0 before 1.14.0."
            }
          ],
          "value": "Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory and CPU via a request body made of many 1-byte chunks.\n\nThe chunked reader in lib/bandit/http1/socket.ex keeps every chunk as its own list cell and binary term until IO.iodata_to_binary/1 joins them, and nothing limits the number of chunks. The :length option of read_body/2 counts only data bytes, so tiny chunks cost far more memory than their payload: 48 MB of 1-byte chunks grew one handler process to about 500 MB and took about 6 s of CPU. The route does not need to read the body, because on keep-alive connections ensure_completed/1 drains unread bodies through the same reader.\n\nThis issue affects bandit: from 0.1.0 before 1.14.0."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-130",
          "descriptions": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "base64": false,
                  "type": "text/html",
                  "value": "\u003cp\u003eAn unauthenticated client can make a single HTTP/1.1 request hold many times its body size in server memory (about 48 MB for a 1 MB body in the reporter\u0027s test), and keep CPU busy while the chunks are joined. This affects any Bandit server that accepts HTTP/1.1 requests, whether or not its routes read the body.\u003c/p\u003e"
                },
                {
                  "base64": false,
                  "type": "text/markdown",
                  "value": "An unauthenticated client can make a single HTTP/1.1 request hold many times its body size in server memory (about 48 MB for a 1 MB body in the reporter\u0027s test), and keep CPU busy while the chunks are joined. This affects any Bandit server that accepts HTTP/1.1 requests, whether or not its routes read the body."
                }
              ],
              "value": "An unauthenticated client can make a single HTTP/1.1 request hold many times its body size in server memory (about 48 MB for a 1 MB body in the reporter\u0027s test), and keep CPU busy while the chunks are joined. This affects any Bandit server that accepts HTTP/1.1 requests, whether or not its routes read the body."
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-770",
              "description": "CWE-770 Allocation of Resources Without Limits or Throttling",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-26T13:31:48.184Z",
        "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "shortName": "EEF"
      },
      "references": [
        {
          "name": "HTTP/1.1 chunked request bodies made of 1-byte chunks amplify memory use in Bandit",
          "tags": [
            "vendor-advisory",
            "related"
          ],
          "url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-jwh3-j29h-qfmw"
        },
        {
          "name": "EEF CNA record for CVE-2026-111101",
          "tags": [
            "related"
          ],
          "url": "https://cna.erlef.org/cves/CVE-2026-111101.html"
        },
        {
          "name": "OSV record EEF-CVE-2026-111101",
          "tags": [
            "related"
          ],
          "url": "https://osv.dev/vulnerability/EEF-CVE-2026-111101"
        },
        {
          "name": "Introducing commit 7201270 in mtrudel/bandit",
          "tags": [
            "related"
          ],
          "url": "https://github.com/mtrudel/bandit/commit/7201270c34b90f6c9e15c0386c2bb802c0c72ab4"
        },
        {
          "name": "Fix commit 220b9df in mtrudel/bandit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "HTTP/1.1 chunked request bodies made of 1-byte chunks amplify memory use in Bandit",
      "workarounds": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eFrom 0.7.0, a server whose clients and proxies all speak HTTP/2 can disable HTTP/1 with \u003ccode\u003ehttp_1_options: [enabled: false]\u003c/code\u003e, so that the vulnerable chunked body reader never runs.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "From 0.7.0, a server whose clients and proxies all speak HTTP/2 can disable HTTP/1 with `http_1_options: [enabled: false]`, so that the vulnerable chunked body reader never runs."
            }
          ],
          "value": "From 0.7.0, a server whose clients and proxies all speak HTTP/2 can disable HTTP/1 with http_1_options: [enabled: false], so that the vulnerable chunked body reader never runs."
        }
      ],
      "x_proofOfConcept": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003col\u003e\n\u003cli\u003eRun Bandit with a Plug that calls \u003ccode\u003ePlug.Conn.read_body(conn, length: 1_000_000, read_length: 1_000_000)\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eSend \u003ccode\u003ePOST /\u003c/code\u003e with \u003ccode\u003eTransfer-Encoding: chunked\u003c/code\u003e and a body of 1,000,000 chunks of \u003ccode\u003e1\\r\\nA\\r\\n\u003c/code\u003e, followed by \u003ccode\u003e0\\r\\n\\r\\n\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eWhen \u003ccode\u003eread_body\u003c/code\u003e returns the 1,000,000 body bytes, the handler process holds about 48 MB and BEAM memory has grown by about 55 MB, for 6 MB sent.\u003c/li\u003e\n\u003c/ol\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "1. Run Bandit with a Plug that calls `Plug.Conn.read_body(conn, length: 1_000_000, read_length: 1_000_000)`.\n2. Send `POST /` with `Transfer-Encoding: chunked` and a body of 1,000,000 chunks of `1\\r\\nA\\r\\n`, followed by `0\\r\\n\\r\\n`.\n3. When `read_body` returns the 1,000,000 body bytes, the handler process holds about 48 MB and BEAM memory has grown by about 55 MB, for 6 MB sent."
            }
          ],
          "value": "* Run Bandit with a Plug that calls Plug.Conn.read_body(conn, length: 1_000_000, read_length: 1_000_000).\n* Send POST / with Transfer-Encoding: chunked and a body of 1,000,000 chunks of 1\\r\\nA\\r\\n, followed by 0\\r\\n\\r\\n.\n* When read_body returns the 1,000,000 body bytes, the handler process holds about 48 MB and BEAM memory has grown by about 55 MB, for 6 MB sent."
        }
      ],
      "x_technicalAnalysis": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003e\u003cstrong\u003e1. Per-chunk accumulation.\u003c/strong\u003e \u003ccode\u003edo_read_chunked_data!\u003c/code\u003e in \u003ccode\u003elib/bandit/http1/socket.ex\u003c/code\u003e collects chunks as \u003ccode\u003e[body | chunk]\u003c/code\u003e, adding a cons cell and a binary term for every chunk.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2. Byte-only limit.\u003c/strong\u003e \u003ccode\u003e:length\u003c/code\u003e limits data bytes, not the number of chunks, so a body of \u003ccode\u003e1\\r\\nx\\r\\n\u003c/code\u003e chunks becomes an 8-million-element improper list before \u003ccode\u003eIO.iodata_to_binary\u003c/code\u003e runs. Sending 48 MB of 1-byte chunks grew the handler heap to about 500 MB and used about 6 s of CPU. The same body as one 8 MB chunk peaked at about 16 MB and took 5 ms.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3. No body read needed.\u003c/strong\u003e On keep-alive connections, \u003ccode\u003eensure_completed/1\u003c/code\u003e drains unread bodies through the same path. Against a Plug that never calls \u003ccode\u003eread_body\u003c/code\u003e, the attack used about 417 MB.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "**1. Per-chunk accumulation.** `do_read_chunked_data!` in `lib/bandit/http1/socket.ex` collects chunks as `[body | chunk]`, adding a cons cell and a binary term for every chunk.\n\n**2. Byte-only limit.** `:length` limits data bytes, not the number of chunks, so a body of `1\\r\\nx\\r\\n` chunks becomes an 8-million-element improper list before `IO.iodata_to_binary` runs. Sending 48 MB of 1-byte chunks grew the handler heap to about 500 MB and used about 6 s of CPU. The same body as one 8 MB chunk peaked at about 16 MB and took 5 ms.\n\n**3. No body read needed.** On keep-alive connections, `ensure_completed/1` drains unread bodies through the same path. Against a Plug that never calls `read_body`, the attack used about 417 MB."
            }
          ],
          "value": "1. Per-chunk accumulation. do_read_chunked_data! in lib/bandit/http1/socket.ex collects chunks as [body | chunk], adding a cons cell and a binary term for every chunk.\n\n2. Byte-only limit. :length limits data bytes, not the number of chunks, so a body of 1\\r\\nx\\r\\n chunks becomes an 8-million-element improper list before IO.iodata_to_binary runs. Sending 48 MB of 1-byte chunks grew the handler heap to about 500 MB and used about 6 s of CPU. The same body as one 8 MB chunk peaked at about 16 MB and took 5 ms.\n\n3. No body read needed. On keep-alive connections, ensure_completed/1 drains unread bodies through the same path. Against a Plug that never calls read_body, the attack used about 417 MB."
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
    "assignerShortName": "EEF",
    "cveId": "CVE-2026-111101",
    "datePublished": "2026-10-26T13:31:48.184Z",
    "dateReserved": "2026-10-23T12:30:01.834Z",
    "dateUpdated": "2026-10-26T15:35:51.401Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-111101\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-10-26T15:10:33.224480Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-10-26T15:32:46.669Z\"}}], \"cna\": {\"title\": \"HTTP/1.1 chunked request bodies made of 1-byte chunks amplify memory use in Bandit\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"reporter\", \"value\": \"Peter Ullrich\"}, {\"lang\": \"en\", \"type\": \"remediation developer\", \"value\": \"Mat Trudel\"}, {\"lang\": \"en\", \"type\": \"analyst\", \"value\": \"Jonatan M\\u00e4nnchen / EEF\"}], \"impacts\": [{\"capecId\": \"CAPEC-130\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"An unauthenticated client can make a single HTTP/1.1 request hold many times its body size in server memory (about 48 MB for a 1 MB body in the reporter\u0027s test), and keep CPU busy while the chunks are joined. This affects any Bandit server that accepts HTTP/1.1 requests, whether or not its routes read the body.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eAn unauthenticated client can make a single HTTP/1.1 request hold many times its body size in server memory (about 48 MB for a 1 MB body in the reporter\u0027s test), and keep CPU busy while the chunks are joined. This affects any Bandit server that accepts HTTP/1.1 requests, whether or not its routes read the body.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"An unauthenticated client can make a single HTTP/1.1 request hold many times its body size in server memory (about 48 MB for a 1 MB body in the reporter\u0027s test), and keep CPU busy while the chunks are joined. This affects any Bandit server that accepts HTTP/1.1 requests, whether or not its routes read the body.\", \"base64\": false}]}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 8.7, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"HIGH\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"cpes\": [\"cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/mtrudel/bandit\", \"vendor\": \"mtrudel\", \"product\": \"bandit\", \"versions\": [{\"status\": \"affected\", \"version\": \"0.1.0\", \"lessThan\": \"1.14.0\", \"versionType\": \"semver\"}], \"packageURL\": \"pkg:hex/bandit\", \"packageName\": \"bandit\", \"collectionURL\": \"https://repo.hex.pm\", \"defaultStatus\": \"unaffected\"}, {\"cpes\": [\"cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/mtrudel/bandit\", \"vendor\": \"mtrudel\", \"product\": \"bandit\", \"versions\": [{\"status\": \"affected\", \"version\": \"7201270c34b90f6c9e15c0386c2bb802c0c72ab4\", \"lessThan\": \"220b9dfd27f9a21305be2afc75cbe585ddc24e7a\", \"versionType\": \"git\"}], \"packageURL\": \"pkg:github/mtrudel/bandit\", \"packageName\": \"mtrudel/bandit\", \"collectionURL\": \"https://github.com\", \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://github.com/mtrudel/bandit/security/advisories/GHSA-jwh3-j29h-qfmw\", \"name\": \"HTTP/1.1 chunked request bodies made of 1-byte chunks amplify memory use in Bandit\", \"tags\": [\"vendor-advisory\", \"related\"]}, {\"url\": \"https://cna.erlef.org/cves/CVE-2026-111101.html\", \"name\": \"EEF CNA record for CVE-2026-111101\", \"tags\": [\"related\"]}, {\"url\": \"https://osv.dev/vulnerability/EEF-CVE-2026-111101\", \"name\": \"OSV record EEF-CVE-2026-111101\", \"tags\": [\"related\"]}, {\"url\": \"https://github.com/mtrudel/bandit/commit/7201270c34b90f6c9e15c0386c2bb802c0c72ab4\", \"name\": \"Introducing commit 7201270 in mtrudel/bandit\", \"tags\": [\"related\"]}, {\"url\": \"https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a\", \"name\": \"Fix commit 220b9df in mtrudel/bandit\", \"tags\": [\"patch\"]}], \"workarounds\": [{\"lang\": \"en\", \"value\": \"From 0.7.0, a server whose clients and proxies all speak HTTP/2 can disable HTTP/1 with http_1_options: [enabled: false], so that the vulnerable chunked body reader never runs.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eFrom 0.7.0, a server whose clients and proxies all speak HTTP/2 can disable HTTP/1 with \u003ccode\u003ehttp_1_options: [enabled: false]\u003c/code\u003e, so that the vulnerable chunked body reader never runs.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"From 0.7.0, a server whose clients and proxies all speak HTTP/2 can disable HTTP/1 with `http_1_options: [enabled: false]`, so that the vulnerable chunked body reader never runs.\", \"base64\": false}]}], \"dateAssigned\": \"2026-10-23T12:35:54.000Z\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory and CPU via a request body made of many 1-byte chunks.\\n\\nThe chunked reader in lib/bandit/http1/socket.ex keeps every chunk as its own list cell and binary term until IO.iodata_to_binary/1 joins them, and nothing limits the number of chunks. The :length option of read_body/2 counts only data bytes, so tiny chunks cost far more memory than their payload: 48 MB of 1-byte chunks grew one handler process to about 500 MB and took about 6 s of CPU. The route does not need to read the body, because on keep-alive connections ensure_completed/1 drains unread bodies through the same reader.\\n\\nThis issue affects bandit: from 0.1.0 before 1.14.0.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eAllocation of Resources Without Limits or Throttling vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory and CPU via a request body made of many 1-byte chunks.\u003c/p\u003e\\n\u003cp\u003eThe chunked reader in \u003ccode\u003elib/bandit/http1/socket.ex\u003c/code\u003e keeps every chunk as its own list cell and binary term until \u003ccode\u003eIO.iodata_to_binary/1\u003c/code\u003e joins them, and nothing limits the number of chunks. The \u003ccode\u003e:length\u003c/code\u003e option of \u003ccode\u003eread_body/2\u003c/code\u003e counts only data bytes, so tiny chunks cost far more memory than their payload: 48 MB of 1-byte chunks grew one handler process to about 500 MB and took about 6 s of CPU. The route does not need to read the body, because on keep-alive connections \u003ccode\u003eensure_completed/1\u003c/code\u003e drains unread bodies through the same reader.\u003c/p\u003e\\n\u003cp\u003eThis issue affects bandit: from 0.1.0 before 1.14.0.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory and CPU via a request body made of many 1-byte chunks.\\n\\nThe chunked reader in `lib/bandit/http1/socket.ex` keeps every chunk as its own list cell and binary term until `IO.iodata_to_binary/1` joins them, and nothing limits the number of chunks. The `:length` option of `read_body/2` counts only data bytes, so tiny chunks cost far more memory than their payload: 48 MB of 1-byte chunks grew one handler process to about 500 MB and took about 6 s of CPU. The route does not need to read the body, because on keep-alive connections `ensure_completed/1` drains unread bodies through the same reader.\\n\\nThis issue affects bandit: from 0.1.0 before 1.14.0.\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-770\", \"description\": \"CWE-770 Allocation of Resources Without Limits or Throttling\"}]}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"1.14.0\", \"versionStartIncluding\": \"0.1.0\"}], \"operator\": \"OR\"}], \"operator\": \"AND\"}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-10-26T13:31:48.184Z\"}, \"x_proofOfConcept\": [{\"lang\": \"en\", \"value\": \"* Run Bandit with a Plug that calls Plug.Conn.read_body(conn, length: 1_000_000, read_length: 1_000_000).\\n* Send POST / with Transfer-Encoding: chunked and a body of 1,000,000 chunks of 1\\\\r\\\\nA\\\\r\\\\n, followed by 0\\\\r\\\\n\\\\r\\\\n.\\n* When read_body returns the 1,000,000 body bytes, the handler process holds about 48 MB and BEAM memory has grown by about 55 MB, for 6 MB sent.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003col\u003e\\n\u003cli\u003eRun Bandit with a Plug that calls \u003ccode\u003ePlug.Conn.read_body(conn, length: 1_000_000, read_length: 1_000_000)\u003c/code\u003e.\u003c/li\u003e\\n\u003cli\u003eSend \u003ccode\u003ePOST /\u003c/code\u003e with \u003ccode\u003eTransfer-Encoding: chunked\u003c/code\u003e and a body of 1,000,000 chunks of \u003ccode\u003e1\\\\r\\\\nA\\\\r\\\\n\u003c/code\u003e, followed by \u003ccode\u003e0\\\\r\\\\n\\\\r\\\\n\u003c/code\u003e.\u003c/li\u003e\\n\u003cli\u003eWhen \u003ccode\u003eread_body\u003c/code\u003e returns the 1,000,000 body bytes, the handler process holds about 48 MB and BEAM memory has grown by about 55 MB, for 6 MB sent.\u003c/li\u003e\\n\u003c/ol\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"1. Run Bandit with a Plug that calls `Plug.Conn.read_body(conn, length: 1_000_000, read_length: 1_000_000)`.\\n2. Send `POST /` with `Transfer-Encoding: chunked` and a body of 1,000,000 chunks of `1\\\\r\\\\nA\\\\r\\\\n`, followed by `0\\\\r\\\\n\\\\r\\\\n`.\\n3. When `read_body` returns the 1,000,000 body bytes, the handler process holds about 48 MB and BEAM memory has grown by about 55 MB, for 6 MB sent.\", \"base64\": false}]}], \"x_technicalAnalysis\": [{\"lang\": \"en\", \"value\": \"1. Per-chunk accumulation. do_read_chunked_data! in lib/bandit/http1/socket.ex collects chunks as [body | chunk], adding a cons cell and a binary term for every chunk.\\n\\n2. Byte-only limit. :length limits data bytes, not the number of chunks, so a body of 1\\\\r\\\\nx\\\\r\\\\n chunks becomes an 8-million-element improper list before IO.iodata_to_binary runs. Sending 48 MB of 1-byte chunks grew the handler heap to about 500 MB and used about 6 s of CPU. The same body as one 8 MB chunk peaked at about 16 MB and took 5 ms.\\n\\n3. No body read needed. On keep-alive connections, ensure_completed/1 drains unread bodies through the same path. Against a Plug that never calls read_body, the attack used about 417 MB.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003e\u003cstrong\u003e1. Per-chunk accumulation.\u003c/strong\u003e \u003ccode\u003edo_read_chunked_data!\u003c/code\u003e in \u003ccode\u003elib/bandit/http1/socket.ex\u003c/code\u003e collects chunks as \u003ccode\u003e[body | chunk]\u003c/code\u003e, adding a cons cell and a binary term for every chunk.\u003c/p\u003e\\n\u003cp\u003e\u003cstrong\u003e2. Byte-only limit.\u003c/strong\u003e \u003ccode\u003e:length\u003c/code\u003e limits data bytes, not the number of chunks, so a body of \u003ccode\u003e1\\\\r\\\\nx\\\\r\\\\n\u003c/code\u003e chunks becomes an 8-million-element improper list before \u003ccode\u003eIO.iodata_to_binary\u003c/code\u003e runs. Sending 48 MB of 1-byte chunks grew the handler heap to about 500 MB and used about 6 s of CPU. The same body as one 8 MB chunk peaked at about 16 MB and took 5 ms.\u003c/p\u003e\\n\u003cp\u003e\u003cstrong\u003e3. No body read needed.\u003c/strong\u003e On keep-alive connections, \u003ccode\u003eensure_completed/1\u003c/code\u003e drains unread bodies through the same path. Against a Plug that never calls \u003ccode\u003eread_body\u003c/code\u003e, the attack used about 417 MB.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"**1. Per-chunk accumulation.** `do_read_chunked_data!` in `lib/bandit/http1/socket.ex` collects chunks as `[body | chunk]`, adding a cons cell and a binary term for every chunk.\\n\\n**2. Byte-only limit.** `:length` limits data bytes, not the number of chunks, so a body of `1\\\\r\\\\nx\\\\r\\\\n` chunks becomes an 8-million-element improper list before `IO.iodata_to_binary` runs. Sending 48 MB of 1-byte chunks grew the handler heap to about 500 MB and used about 6 s of CPU. The same body as one 8 MB chunk peaked at about 16 MB and took 5 ms.\\n\\n**3. No body read needed.** On keep-alive connections, `ensure_completed/1` drains unread bodies through the same path. Against a Plug that never calls `read_body`, the attack used about 417 MB.\", \"base64\": false}]}]}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-111101\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-26T15:35:51.401Z\", \"dateReserved\": \"2026-10-23T12:30:01.834Z\", \"assignerOrgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"datePublished\": \"2026-10-26T13:31:48.184Z\", \"assignerShortName\": \"EEF\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}