CVE-2026-47066

Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation. The Alt-Svc response header parser in src/hackney_altsvc.erl does not guarantee forward progress. When parse_token/2 receives a non-token, non-whitespace, non-comma byte (e.g. !, @, =, ;), it returns the input unchanged. skip_comma/1 also returns the buffer unchanged when the first byte is not a comma. parse_entries/2 then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns. The entry point parse_and_cache/3 is called synchronously in the connection process on every HTTP response. A single-byte Alt-Svc: ! response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to. This issue affects hackney: from 2.0.0-beta.1 before 4.0.1.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://cna.erlef.org/cves/CVE-2026-47066.html	Patch Third Party Advisory
https://github.com/benoitc/hackney/commit/e548aba1f97ffa3f4750da7b772998fb78c01894	Patch
https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j	Exploit Patch Vendor Advisory
https://osv.dev/vulnerability/EEF-CVE-2026-47066	Patch Third Party Advisory
https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j	Exploit Patch Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-05-25 15:16

Updated : 2026-07-24 10:10

NVD link : CVE-2026-47066

Mitre link : CVE-2026-47066

CVE.ORG link : CVE-2026-47066

JSON object : View

Products Affected

benoitc

hackney

CWE

CWE-835

Loop with Unreachable Exit Condition ('Infinite Loop')

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"description": [{"lang": "en", "value": "CWE-835"}]}], "descriptions": [{"lang": "en", "value": "Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation. The Alt-Svc response header parser in src/hackney_altsvc.erl does not guarantee forward progress. When parse_token/2 receives a non-token, non-whitespace, non-comma byte (e.g. !, @, =, ;), it returns the input unchanged. skip_comma/1 also returns the buffer unchanged when the first byte is not a comma. parse_entries/2 then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns.\n\nThe entry point parse_and_cache/3 is called synchronously in the connection process on every HTTP response. A single-byte Alt-Svc: ! response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to.\n\nThis issue affects hackney: from 2.0.0-beta.1 before 4.0.1."}, {"lang": "es", "value": "Vulnerabilidad de bucle con condici\u00f3n de salida inalcanzable ('Bucle Infinito') en benoitc hackney permite asignaci\u00f3n excesiva. El analizador de encabezados de respuesta Alt-Svc en src/hackney_altsvc.erl no garantiza el progreso hacia adelante. Cuando parse_token/2 recibe un byte que no es un token, no es un espacio en blanco, no es una coma (p. ej. '!', '@', '=', ';'), devuelve la entrada sin cambios. skip_comma/1 tambi\u00e9n devuelve el b\u00fafer sin cambios cuando el primer byte no es una coma. parse_entries/2 luego recurre con datos id\u00e9nticos, creando un bucle recursivo de cola infinito y ajustado que fija un planificador al 100% de CPU. El proceso de llamada nunca regresa.\n\nEl punto de entrada parse_and_cache/3 se llama sincr\u00f3nicamente en el proceso de conexi\u00f3n en cada respuesta HTTP. Un encabezado de respuesta Alt-Svc: '!' de un solo byte es suficiente para activar el bloqueo; el encabezado est\u00e1 totalmente controlado por cualquier origen HTTP al que se conecta el cliente.\n\nEste problema afecta a hackney: desde 2.0.0-beta.1 antes de 4.0.1."}], "lastModified": "2026-07-24T10:10:00.197", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B119C170-E9CA-4AEE-BE04-F074E70CBF82", "versionEndExcluding": "4.0.1", "versionStartIncluding": "2.0.0"}], "operator": "OR"}]}], "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}