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)

cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*

History

26 Jun 2026, 02:39

Type	Values Removed	Values Added
First Time		Haproxy Haproxy haproxy
References	~~() https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513 -~~	() https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513 - Patch
References	~~() https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function -~~	() https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function - Third Party Advisory
CPE		cpe:2.3:a:haproxy:haproxy::::::::

18 Jun 2026, 18:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-18 17:16

Updated : 2026-07-14 22:17

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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