High 7.5Published Jun 18, 2026

CVE-2026-55204HAProxy - NULL Pointer Dereference in hpack_dht_insert Function

Updated under an hour ago (Oct 27, 2026, 2:00 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-476
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: VulnCheck
NVD analysis: Analyzed
Record last updated: Jul 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

haproxy haproxy haproxy:haproxy (from the name)	through 3.4.0; 9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513 not affected	CNA record
haproxy haproxy haproxy:haproxy	before 2.4.36; from 2.5 before 2.6.30; from 2.7 before 2.8.25; from 2.9 before 3.0.24; from 3.1 before 3.2.20; from 3.3 before 3.4.1	NVD

References

References

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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.