{"id":"CVE-2026-55204","aliases":["BIT-haproxy-2026-55204"],"url":"https://o3.security/vulnerability/CVE-2026-55204","summary":"HAProxy - NULL Pointer Dereference in hpack_dht_insert Function","details":"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.","published":"2026-06-18T16:05:52.058Z","modified":"2026-08-18T13:27:13.933103426Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[],"fix":{"url":"https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513","label":"haproxy/haproxy@9a6d1fe"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55204.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55204"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function"},{"type":"FIX","url":"https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513"},{"type":"PACKAGE","url":"https://github.com/haproxy/haproxy"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-18T13:27:13.933103426Z"}}