What is CVE-2026-55204?

CVE-2026-55204 is a high-severity vulnerability in Haproxy, classified under NULL Pointer Dereference. CVSS score: 7.5/10. Published 2026-06-18.

How severe is CVE-2026-55204?

High severity. CVSS v3 base score is 7.5 out of 10.

NULL pointer dereference in Haproxy

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…

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Haproxy — versions 0, 9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513

Weakness classification (CWE)

CWE-476 — NULL Pointer Dereference

References

disclosure@vulncheck.com (patch)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-55204?: CVE-2026-55204 is a high-severity vulnerability in Haproxy, classified under NULL Pointer Dereference. CVSS score: 7.5/10. Published 2026-06-18.
How severe is CVE-2026-55204?: High severity. CVSS v3 base score is 7.5 out of 10.