CVE-2026-55204

HAProxy through 3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under memory pressure to dereference a NULL pointer and crash HAProxy worker processes, causing denial of service.

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://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513	Patch
https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function	Third Party Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:haproxy:haproxy::::::::
	cpe:2.3:a:haproxy:haproxy::::::::
	cpe:2.3:a:haproxy:haproxy::::::::
	cpe:2.3:a:haproxy:haproxy::::::::
	cpe:2.3:a:haproxy:haproxy::::::::
	cpe:2.3:a:haproxy:haproxy::::::::

History

26 Oct 2026, 11:10

Type	Values Removed	Values Added
Summary		(es) HAProxy hasta la versión 3.4.0, corregido en el commit 9a6d1fe, contiene una vulnerabilidad de desreferencia de puntero nulo en hpack_dht_insert() dentro de src/hpack-tbl.c que no valida el valor de retorno de hpack_dht_defrag() cuando el pool de memoria está agotado. Un atacante puede desencadenar inserciones en la tabla dinámica HPACK bajo presión de memoria para desreferenciar un puntero NULO y bloquear los procesos de trabajador de HAProxy, causando denegación de servicio.

Information

Published : 2026-06-18 17:16

Updated : 2026-10-26 11:10

NVD link : CVE-2026-55204

Mitre link : CVE-2026-55204

CVE.ORG link : CVE-2026-55204

JSON object : View

Products Affected

haproxy

haproxy

CWE

CWE-476

NULL Pointer Dereference

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Un atacante puede desencadenar inserciones en la tabla din\u00e1mica HPACK bajo presi\u00f3n de memoria para desreferenciar un puntero NULO y bloquear los procesos de trabajador de HAProxy, causando denegaci\u00f3n de servicio."}], "lastModified": "2026-10-26T11:10:00.157", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "88E7AA4A-F1FA-4F49-A292-438B28F462C9", "versionEndExcluding": "2.4.36"}, {"criteria": "cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "2D8EB6E1-7127-4DD4-A00B-442795722F1A", "versionEndExcluding": "2.6.30", "versionStartIncluding": "2.5"}, {"criteria": "cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "AEE6ECD6-2498-4961-A27F-9B12379C8CC6", "versionEndExcluding": "2.8.25", "versionStartIncluding": "2.7"}, {"criteria": "cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "DE40B7E0-830C-4D4E-ACDF-97C503312707", "versionEndExcluding": "3.0.24", "versionStartIncluding": "2.9"}, {"criteria": "cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "60DCBD0D-4201-4AAD-A6D3-178F8412EB44", "versionEndExcluding": "3.2.20", "versionStartIncluding": "3.1"}, {"criteria": "cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6D9D0A12-A3D0-4E8D-BB1C-F964910A004D", "versionEndExcluding": "3.4.1", "versionStartIncluding": "3.3"}], "operator": "OR"}]}], "sourceIdentifier": "disclosure@vulncheck.com"}