CVE-2026-55204
Description
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.
How to fix CVE-2026-55204
No fixed version has been published yet. Mitigate by removing the affected package or applying upstream guidance from the references below.
- Debian/haproxy—no fix listed
Is CVE-2026-55204 being exploited?
No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-55204.
Affected packages (1)
- from 0