Name: CVE-2026-55204: NULL Pointer Dereference
Creator: Rapid7
Published: 2026-06-18T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2026-55204, CWE-476, CVSS 7.5, EPSS 0.00484

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 Details

CVSS 4.0 Base Score: 8.7 (HIGH)
CVSS 4.0 Vector: (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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X)
CVSS 3.1 Base Score: 7.5
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Alma_linux	—	Upgrade haproxy	Oct 11, 2026	Aug 17, 2026
Amazon_linux_2023	—	Upgrade haproxy-debuginfoUpgrade haproxy-debugsourceUpgrade haproxy	Jul 8, 2026	Jun 18, 2026
Oracle_linux	—	Upgrade haproxy	Oct 22, 2026	Jun 18, 2026
Redhat_linux	—	No solution existsUpgrade haproxy-debugsourceUpgrade haproxy-debuginfoUpgrade haproxy	Jul 20, 2026	Jun 18, 2026
Rocky_linux	—	Upgrade haproxy-debuginfoUpgrade haproxyUpgrade haproxy-debugsource	Aug 20, 2026	Aug 18, 2026
Ubuntu	—	Upgrade haproxy	Jun 23, 2026	Jun 22, 2026

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CVSS Details

Covered by Rapid7

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