CVE-2026-39803 (GCVE-0-2026-39803)
Vulnerability from cvelistv5
Published
2026-05-13 13:36
Modified
2026-05-27 15:40
Severity ?
VLAI Severity ?
EPSS score ?
CWE
- CWE-770 - Allocation of Resources Without Limits or Throttling
Summary
Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.
The chunked clause of 'Elixir.Bandit.HTTP1.Socket':read_data/2 in lib/bandit/http1/socket.ex ignores the caller-supplied :length option when reading HTTP/1 chunked request bodies. Instead of capping the accumulated body at the configured limit (e.g. Plug.Parsers' default 8 MB), do_read_chunked_data!/5 buffers every received chunk into an iolist unconditionally and materializes the entire body as a single binary. The function always returns {:ok, body, ...}, so callers cannot interpose a 413 response.
Because Plug.Parsers runs before routing and authentication in the standard Phoenix endpoint, an unauthenticated attacker needs no valid route or credentials. Sending a single Transfer-Encoding: chunked POST request with an arbitrarily large body to any path causes the BEAM process to exhaust available memory and be terminated by the OS OOM killer.
The content-length path in the same function correctly enforces the limit and is not affected.
This issue affects bandit: from 1.4.0 before 1.11.1.
References
| URL | Tags | |
|---|---|---|
Impacted products
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-39803",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-13T14:41:58.440838Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-05-13T14:43:25.158Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"references": [
{
"tags": [
"exploit"
],
"url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-9q9q-324x-93r2"
}
],
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"collectionURL": "https://repo.hex.pm",
"cpes": [
"cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Bandit.HTTP1.Socket\u0027"
],
"packageName": "bandit",
"packageURL": "pkg:hex/bandit",
"product": "bandit",
"programFiles": [
"lib/bandit/http1/socket.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Bandit.HTTP1.Socket\u0027:read_data/2"
},
{
"name": "\u0027Elixir.Bandit.HTTP1.Socket\u0027:do_read_chunked_data!/5"
}
],
"repo": "https://github.com/mtrudel/bandit",
"vendor": "mtrudel",
"versions": [
{
"lessThan": "1.11.1",
"status": "affected",
"version": "1.4.0",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Bandit.HTTP1.Socket\u0027"
],
"packageName": "mtrudel/bandit",
"packageURL": "pkg:github/mtrudel/bandit",
"product": "bandit",
"programFiles": [
"lib/bandit/http1/socket.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Bandit.HTTP1.Socket\u0027:read_data/2"
},
{
"name": "\u0027Elixir.Bandit.HTTP1.Socket\u0027:do_read_chunked_data!/5"
}
],
"repo": "https://github.com/mtrudel/bandit",
"vendor": "mtrudel",
"versions": [
{
"lessThan": "ae3520dfdbfab115c638f8c7f6f6b805db34e1ab",
"status": "affected",
"version": "903e209a521bc216b9f9065c01ae9a0cac2d5a10",
"versionType": "git"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*",
"versionEndExcluding": "1.11.1",
"versionStartIncluding": "1.4.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "AND"
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Peter Ullrich"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Mat Trudel"
},
{
"lang": "en",
"type": "analyst",
"value": "Jonatan M\u00e4nnchen / EEF"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.\u003cp\u003eThe chunked clause of \u003ctt\u003e\u0027Elixir.Bandit.HTTP1.Socket\u0027:read_data/2\u003c/tt\u003e in \u003ctt\u003elib/bandit/http1/socket.ex\u003c/tt\u003e ignores the caller-supplied \u003ctt\u003e:length\u003c/tt\u003e option when reading HTTP/1 chunked request bodies. Instead of capping the accumulated body at the configured limit (e.g. \u003ctt\u003ePlug.Parsers\u003c/tt\u003e\u0027 default 8 MB), \u003ctt\u003edo_read_chunked_data!/5\u003c/tt\u003e buffers every received chunk into an iolist unconditionally and materializes the entire body as a single binary. The function always returns \u003ctt\u003e{:ok, body, ...}\u003c/tt\u003e, so callers cannot interpose a 413 response.\u003c/p\u003e\u003cp\u003eBecause \u003ctt\u003ePlug.Parsers\u003c/tt\u003e runs before routing and authentication in the standard Phoenix endpoint, an unauthenticated attacker needs no valid route or credentials. Sending a single \u003ctt\u003eTransfer-Encoding: chunked\u003c/tt\u003e POST request with an arbitrarily large body to any path causes the BEAM process to exhaust available memory and be terminated by the OS OOM killer.\u003c/p\u003e\u003cp\u003eThe content-length path in the same function correctly enforces the limit and is not affected.\u003c/p\u003e\u003cp\u003eThis issue affects bandit: from 1.4.0 before 1.11.1.\u003c/p\u003e"
}
],
"value": "Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.\n\nThe chunked clause of \u0027Elixir.Bandit.HTTP1.Socket\u0027:read_data/2 in lib/bandit/http1/socket.ex ignores the caller-supplied :length option when reading HTTP/1 chunked request bodies. Instead of capping the accumulated body at the configured limit (e.g. Plug.Parsers\u0027 default 8 MB), do_read_chunked_data!/5 buffers every received chunk into an iolist unconditionally and materializes the entire body as a single binary. The function always returns {:ok, body, ...}, so callers cannot interpose a 413 response.\n\nBecause Plug.Parsers runs before routing and authentication in the standard Phoenix endpoint, an unauthenticated attacker needs no valid route or credentials. Sending a single Transfer-Encoding: chunked POST request with an arbitrarily large body to any path causes the BEAM process to exhaust available memory and be terminated by the OS OOM killer.\n\nThe content-length path in the same function correctly enforces the limit and is not affected.\n\nThis issue affects bandit: from 1.4.0 before 1.11.1."
}
],
"impacts": [
{
"capecId": "CAPEC-130",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-130 Excessive Allocation"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 8.7,
"baseSeverity": "HIGH",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"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"
},
"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": "2026-05-27T15:40:37.538Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"tags": [
"vendor-advisory",
"related"
],
"url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-9q9q-324x-93r2"
},
{
"tags": [
"related"
],
"url": "https://cna.erlef.org/cves/CVE-2026-39803.html"
},
{
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-39803"
},
{
"tags": [
"patch"
],
"url": "https://github.com/mtrudel/bandit/commit/ae3520dfdbfab115c638f8c7f6f6b805db34e1ab"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "HTTP/1 chunked body reader ignores length cap in bandit",
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-39803",
"datePublished": "2026-05-13T13:36:09.648Z",
"dateReserved": "2026-04-07T12:28:54.916Z",
"dateUpdated": "2026-05-27T15:40:37.538Z",
"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-2026-39803\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-05-13T14:41:58.440838Z\"}}}], \"references\": [{\"url\": \"https://github.com/mtrudel/bandit/security/advisories/GHSA-9q9q-324x-93r2\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-05-13T14:41:29.954Z\"}}], \"cna\": {\"title\": \"HTTP/1 chunked body reader ignores length cap in bandit\", \"source\": {\"discovery\": \"EXTERNAL\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"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\": \"CAPEC-130 Excessive Allocation\"}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"version\": \"4.0\", \"baseScore\": 8.7, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"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\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"HIGH\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"cpes\": [\"cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/mtrudel/bandit\", \"vendor\": \"mtrudel\", \"modules\": [\"\u0027Elixir.Bandit.HTTP1.Socket\u0027\"], \"product\": \"bandit\", \"versions\": [{\"status\": \"affected\", \"version\": \"1.4.0\", \"lessThan\": \"1.11.1\", \"versionType\": \"semver\"}], \"packageURL\": \"pkg:hex/bandit\", \"packageName\": \"bandit\", \"programFiles\": [\"lib/bandit/http1/socket.ex\"], \"collectionURL\": \"https://repo.hex.pm\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"\u0027Elixir.Bandit.HTTP1.Socket\u0027:read_data/2\"}, {\"name\": \"\u0027Elixir.Bandit.HTTP1.Socket\u0027:do_read_chunked_data!/5\"}]}, {\"cpes\": [\"cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/mtrudel/bandit\", \"vendor\": \"mtrudel\", \"modules\": [\"\u0027Elixir.Bandit.HTTP1.Socket\u0027\"], \"product\": \"bandit\", \"versions\": [{\"status\": \"affected\", \"version\": \"903e209a521bc216b9f9065c01ae9a0cac2d5a10\", \"lessThan\": \"ae3520dfdbfab115c638f8c7f6f6b805db34e1ab\", \"versionType\": \"git\"}], \"packageURL\": \"pkg:github/mtrudel/bandit\", \"packageName\": \"mtrudel/bandit\", \"programFiles\": [\"lib/bandit/http1/socket.ex\"], \"collectionURL\": \"https://github.com\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"\u0027Elixir.Bandit.HTTP1.Socket\u0027:read_data/2\"}, {\"name\": \"\u0027Elixir.Bandit.HTTP1.Socket\u0027:do_read_chunked_data!/5\"}]}], \"references\": [{\"url\": \"https://github.com/mtrudel/bandit/security/advisories/GHSA-9q9q-324x-93r2\", \"tags\": [\"vendor-advisory\", \"related\"]}, {\"url\": \"https://cna.erlef.org/cves/CVE-2026-39803.html\", \"tags\": [\"related\"]}, {\"url\": \"https://osv.dev/vulnerability/EEF-CVE-2026-39803\", \"tags\": [\"related\"]}, {\"url\": \"https://github.com/mtrudel/bandit/commit/ae3520dfdbfab115c638f8c7f6f6b805db34e1ab\", \"tags\": [\"patch\"]}], \"x_generator\": {\"engine\": \"cvelib 1.8.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.\\n\\nThe chunked clause of \u0027Elixir.Bandit.HTTP1.Socket\u0027:read_data/2 in lib/bandit/http1/socket.ex ignores the caller-supplied :length option when reading HTTP/1 chunked request bodies. Instead of capping the accumulated body at the configured limit (e.g. Plug.Parsers\u0027 default 8 MB), do_read_chunked_data!/5 buffers every received chunk into an iolist unconditionally and materializes the entire body as a single binary. The function always returns {:ok, body, ...}, so callers cannot interpose a 413 response.\\n\\nBecause Plug.Parsers runs before routing and authentication in the standard Phoenix endpoint, an unauthenticated attacker needs no valid route or credentials. Sending a single Transfer-Encoding: chunked POST request with an arbitrarily large body to any path causes the BEAM process to exhaust available memory and be terminated by the OS OOM killer.\\n\\nThe content-length path in the same function correctly enforces the limit and is not affected.\\n\\nThis issue affects bandit: from 1.4.0 before 1.11.1.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.\u003cp\u003eThe chunked clause of \u003ctt\u003e\u0027Elixir.Bandit.HTTP1.Socket\u0027:read_data/2\u003c/tt\u003e in \u003ctt\u003elib/bandit/http1/socket.ex\u003c/tt\u003e ignores the caller-supplied \u003ctt\u003e:length\u003c/tt\u003e option when reading HTTP/1 chunked request bodies. Instead of capping the accumulated body at the configured limit (e.g. \u003ctt\u003ePlug.Parsers\u003c/tt\u003e\u0027 default 8 MB), \u003ctt\u003edo_read_chunked_data!/5\u003c/tt\u003e buffers every received chunk into an iolist unconditionally and materializes the entire body as a single binary. The function always returns \u003ctt\u003e{:ok, body, ...}\u003c/tt\u003e, so callers cannot interpose a 413 response.\u003c/p\u003e\u003cp\u003eBecause \u003ctt\u003ePlug.Parsers\u003c/tt\u003e runs before routing and authentication in the standard Phoenix endpoint, an unauthenticated attacker needs no valid route or credentials. Sending a single \u003ctt\u003eTransfer-Encoding: chunked\u003c/tt\u003e POST request with an arbitrarily large body to any path causes the BEAM process to exhaust available memory and be terminated by the OS OOM killer.\u003c/p\u003e\u003cp\u003eThe content-length path in the same function correctly enforces the limit and is not affected.\u003c/p\u003e\u003cp\u003eThis issue affects bandit: from 1.4.0 before 1.11.1.\u003c/p\u003e\", \"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\": \"1.11.1\", \"versionStartIncluding\": \"1.4.0\"}], \"operator\": \"OR\"}], \"operator\": \"AND\"}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-05-27T15:40:37.538Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-39803\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-05-27T15:40:37.538Z\", \"dateReserved\": \"2026-04-07T12:28:54.916Z\", \"assignerOrgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"datePublished\": \"2026-05-13T13:36:09.648Z\", \"assignerShortName\": \"EEF\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…