CVE-2026-65624 (GCVE-0-2026-65624)
Vulnerability from cvelistv5
Published
2026-07-28 10:01
Modified
2026-07-29 04:17
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 ninenines cowboy allows an unauthenticated remote attacker to exhaust connection process memory over HTTP/1.1.
The HTTP/1.1 handler in cowboy_http enforces the max_headers limit by counting the number of distinct header names in a map (maps:size(Headers)). When a request contains multiple header lines with the same name, the values are concatenated into a single ever-growing binary stored under that one map key (", " for regular headers, "; " for cookies), so the map size stays at one and the max_headers cap (default 100) is never reached. Because no accumulator bounds the total number of header lines or the total byte size of the header block (only per-line max_header_name_length and max_header_value_length apply), an unauthenticated client can send an arbitrary number of header lines with the same name and grow the connection process's binary memory to arbitrary size within the request window.
The impact per connection is bounded by request_timeout (default 5 seconds, not reset by header data), and by max_heap_size when set (the offending connection process is killed once its heap grows past the limit). When max_heap_size is left at the default (unset), sustained abuse can drive the Erlang VM into out-of-memory conditions.
This issue affects cowboy from 2.0.0-pre.4 before 2.18.0.
References
| URL | Tags | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||
Impacted products
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-65624",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-28T12:38:53.899266Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-07-28T12:39:27.067Z",
"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:ninenines:cowboy:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"cowboy_http"
],
"packageName": "cowboy",
"packageURL": "pkg:hex/cowboy",
"product": "cowboy",
"programFiles": [
"src/cowboy_http.erl"
],
"programRoutines": [
{
"name": "cowboy_http:parse_header/3"
},
{
"name": "cowboy_http:parse_hd_value/6"
}
],
"repo": "https://github.com/ninenines/cowboy",
"vendor": "ninenines",
"versions": [
{
"lessThan": "2.18.0",
"status": "affected",
"version": "2.0.0-pre.4",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:ninenines:cowboy:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"cowboy_http"
],
"packageName": "ninenines/cowboy",
"packageURL": "pkg:github/ninenines/cowboy",
"product": "cowboy",
"programFiles": [
"src/cowboy_http.erl"
],
"programRoutines": [
{
"name": "cowboy_http:parse_header/3"
},
{
"name": "cowboy_http:parse_hd_value/6"
}
],
"repo": "https://github.com/ninenines/cowboy",
"vendor": "ninenines",
"versions": [
{
"lessThan": "3a34d8c1cfd94326466aa16a9017236691dc9c55",
"status": "affected",
"version": "309780a9fda145c262a47ac7811ffd50a0271c5b",
"versionType": "git"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:ninenines:cowboy:*:*:*:*:*:*:*:*",
"versionEndExcluding": "2.18.0",
"versionStartIncluding": "2.0.0-pre.4",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "AND"
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Qiyi Deng / Wuhan University"
},
{
"lang": "en",
"type": "finder",
"value": "Min Shi / Wuhan University"
},
{
"lang": "en",
"type": "finder",
"value": "Yongkang Xiao / Wuhan University"
},
{
"lang": "en",
"type": "finder",
"value": "Jing Chen / Wuhan University"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Lo\u00efc Hoguin"
},
{
"lang": "en",
"type": "analyst",
"value": "Jonatan M\u00e4nnchen / EEF"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eAllocation of Resources Without Limits or Throttling vulnerability in ninenines cowboy allows an unauthenticated remote attacker to exhaust connection process memory over HTTP/1.1.\u003c/p\u003e\u003cp\u003eThe HTTP/1.1 handler in \u003ctt\u003ecowboy_http\u003c/tt\u003e enforces the \u003ctt\u003emax_headers\u003c/tt\u003e limit by counting the number of distinct header names in a map (\u003ctt\u003emaps:size(Headers)\u003c/tt\u003e). When a request contains multiple header lines with the same name, the values are concatenated into a single ever-growing binary stored under that one map key (\u003ctt\u003e\", \"\u003c/tt\u003e for regular headers, \u003ctt\u003e\"; \"\u003c/tt\u003e for cookies), so the map size stays at one and the \u003ctt\u003emax_headers\u003c/tt\u003e cap (default 100) is never reached. Because no accumulator bounds the total number of header lines or the total byte size of the header block (only per-line \u003ctt\u003emax_header_name_length\u003c/tt\u003e and \u003ctt\u003emax_header_value_length\u003c/tt\u003e apply), an unauthenticated client can send an arbitrary number of header lines with the same name and grow the connection process\u0027s binary memory to arbitrary size within the request window.\u003c/p\u003e\u003cp\u003eThe impact per connection is bounded by \u003ctt\u003erequest_timeout\u003c/tt\u003e (default 5 seconds, not reset by header data), and by \u003ctt\u003emax_heap_size\u003c/tt\u003e when set (the offending connection process is killed once its heap grows past the limit). When \u003ctt\u003emax_heap_size\u003c/tt\u003e is left at the default (unset), sustained abuse can drive the Erlang VM into out-of-memory conditions.\u003c/p\u003e\u003cp\u003eThis issue affects cowboy from 2.0.0-pre.4 before 2.18.0.\u003c/p\u003e"
}
],
"value": "Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowboy allows an unauthenticated remote attacker to exhaust connection process memory over HTTP/1.1.\n\nThe HTTP/1.1 handler in cowboy_http enforces the max_headers limit by counting the number of distinct header names in a map (maps:size(Headers)). When a request contains multiple header lines with the same name, the values are concatenated into a single ever-growing binary stored under that one map key (\", \" for regular headers, \"; \" for cookies), so the map size stays at one and the max_headers cap (default 100) is never reached. Because no accumulator bounds the total number of header lines or the total byte size of the header block (only per-line max_header_name_length and max_header_value_length apply), an unauthenticated client can send an arbitrary number of header lines with the same name and grow the connection process\u0027s binary memory to arbitrary size within the request window.\n\nThe impact per connection is bounded by request_timeout (default 5 seconds, not reset by header data), and by max_heap_size when set (the offending connection process is killed once its heap grows past the limit). When max_heap_size is left at the default (unset), sustained abuse can drive the Erlang VM into out-of-memory conditions.\n\nThis issue affects cowboy from 2.0.0-pre.4 before 2.18.0."
}
],
"impacts": [
{
"capecId": "CAPEC-130",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-130 Excessive Allocation"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"attackVector": "NETWORK",
"baseScore": 6.9,
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
"version": "4.0"
},
"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": "2026-07-29T04:17:22.788Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"tags": [
"related",
"third-party-advisory"
],
"url": "https://cna.erlef.org/cves/CVE-2026-65624.html"
},
{
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-65624"
},
{
"tags": [
"patch"
],
"url": "https://github.com/ninenines/cowboy/commit/3a34d8c1cfd94326466aa16a9017236691dc9c55"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "Cowboy HTTP/1.1 max_headers Bypass via Duplicate Header Names Enables Memory Exhaustion",
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-65624",
"datePublished": "2026-07-28T10:01:01.811Z",
"dateReserved": "2026-07-22T13:55:59.401Z",
"dateUpdated": "2026-07-29T04:17:22.788Z",
"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-2026-65624\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-07-28T12:38:53.899266Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-07-28T12:39:19.571Z\"}}], \"cna\": {\"title\": \"Cowboy HTTP/1.1 max_headers Bypass via Duplicate Header Names Enables Memory Exhaustion\", \"source\": {\"discovery\": \"EXTERNAL\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Qiyi Deng / Wuhan University\"}, {\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Min Shi / Wuhan University\"}, {\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Yongkang Xiao / Wuhan University\"}, {\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Jing Chen / Wuhan University\"}, {\"lang\": \"en\", \"type\": \"remediation developer\", \"value\": \"Lo\\u00efc Hoguin\"}, {\"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\": 6.9, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"cpes\": [\"cpe:2.3:a:ninenines:cowboy:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/ninenines/cowboy\", \"vendor\": \"ninenines\", \"modules\": [\"cowboy_http\"], \"product\": \"cowboy\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.0.0-pre.4\", \"lessThan\": \"2.18.0\", \"versionType\": \"semver\"}], \"packageURL\": \"pkg:hex/cowboy\", \"packageName\": \"cowboy\", \"programFiles\": [\"src/cowboy_http.erl\"], \"collectionURL\": \"https://repo.hex.pm\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"cowboy_http:parse_header/3\"}, {\"name\": \"cowboy_http:parse_hd_value/6\"}]}, {\"cpes\": [\"cpe:2.3:a:ninenines:cowboy:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/ninenines/cowboy\", \"vendor\": \"ninenines\", \"modules\": [\"cowboy_http\"], \"product\": \"cowboy\", \"versions\": [{\"status\": \"affected\", \"version\": \"309780a9fda145c262a47ac7811ffd50a0271c5b\", \"lessThan\": \"3a34d8c1cfd94326466aa16a9017236691dc9c55\", \"versionType\": \"git\"}], \"packageURL\": \"pkg:github/ninenines/cowboy\", \"packageName\": \"ninenines/cowboy\", \"programFiles\": [\"src/cowboy_http.erl\"], \"collectionURL\": \"https://github.com\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"cowboy_http:parse_header/3\"}, {\"name\": \"cowboy_http:parse_hd_value/6\"}]}], \"references\": [{\"url\": \"https://cna.erlef.org/cves/CVE-2026-65624.html\", \"tags\": [\"related\", \"third-party-advisory\"]}, {\"url\": \"https://osv.dev/vulnerability/EEF-CVE-2026-65624\", \"tags\": [\"related\"]}, {\"url\": \"https://github.com/ninenines/cowboy/commit/3a34d8c1cfd94326466aa16a9017236691dc9c55\", \"tags\": [\"patch\"]}], \"x_generator\": {\"engine\": \"cvelib 1.8.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowboy allows an unauthenticated remote attacker to exhaust connection process memory over HTTP/1.1.\\n\\nThe HTTP/1.1 handler in cowboy_http enforces the max_headers limit by counting the number of distinct header names in a map (maps:size(Headers)). When a request contains multiple header lines with the same name, the values are concatenated into a single ever-growing binary stored under that one map key (\\\", \\\" for regular headers, \\\"; \\\" for cookies), so the map size stays at one and the max_headers cap (default 100) is never reached. Because no accumulator bounds the total number of header lines or the total byte size of the header block (only per-line max_header_name_length and max_header_value_length apply), an unauthenticated client can send an arbitrary number of header lines with the same name and grow the connection process\u0027s binary memory to arbitrary size within the request window.\\n\\nThe impact per connection is bounded by request_timeout (default 5 seconds, not reset by header data), and by max_heap_size when set (the offending connection process is killed once its heap grows past the limit). When max_heap_size is left at the default (unset), sustained abuse can drive the Erlang VM into out-of-memory conditions.\\n\\nThis issue affects cowboy from 2.0.0-pre.4 before 2.18.0.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eAllocation of Resources Without Limits or Throttling vulnerability in ninenines cowboy allows an unauthenticated remote attacker to exhaust connection process memory over HTTP/1.1.\u003c/p\u003e\u003cp\u003eThe HTTP/1.1 handler in \u003ctt\u003ecowboy_http\u003c/tt\u003e enforces the \u003ctt\u003emax_headers\u003c/tt\u003e limit by counting the number of distinct header names in a map (\u003ctt\u003emaps:size(Headers)\u003c/tt\u003e). When a request contains multiple header lines with the same name, the values are concatenated into a single ever-growing binary stored under that one map key (\u003ctt\u003e\\\", \\\"\u003c/tt\u003e for regular headers, \u003ctt\u003e\\\"; \\\"\u003c/tt\u003e for cookies), so the map size stays at one and the \u003ctt\u003emax_headers\u003c/tt\u003e cap (default 100) is never reached. Because no accumulator bounds the total number of header lines or the total byte size of the header block (only per-line \u003ctt\u003emax_header_name_length\u003c/tt\u003e and \u003ctt\u003emax_header_value_length\u003c/tt\u003e apply), an unauthenticated client can send an arbitrary number of header lines with the same name and grow the connection process\u0027s binary memory to arbitrary size within the request window.\u003c/p\u003e\u003cp\u003eThe impact per connection is bounded by \u003ctt\u003erequest_timeout\u003c/tt\u003e (default 5 seconds, not reset by header data), and by \u003ctt\u003emax_heap_size\u003c/tt\u003e when set (the offending connection process is killed once its heap grows past the limit). When \u003ctt\u003emax_heap_size\u003c/tt\u003e is left at the default (unset), sustained abuse can drive the Erlang VM into out-of-memory conditions.\u003c/p\u003e\u003cp\u003eThis issue affects cowboy from 2.0.0-pre.4 before 2.18.0.\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:ninenines:cowboy:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"2.18.0\", \"versionStartIncluding\": \"2.0.0-pre.4\"}], \"operator\": \"OR\"}], \"operator\": \"AND\"}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-07-29T04:17:22.788Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-65624\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-07-29T04:17:22.788Z\", \"dateReserved\": \"2026-07-22T13:55:59.401Z\", \"assignerOrgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"datePublished\": \"2026-07-28T10:01:01.811Z\", \"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…