HAProxy through 3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpackdhtinsert() within src/hpack-tbl.c that fails to validate the return value of hpackdhtdefrag() 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.
{
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55204.json",
"cwe_ids": [
"CWE-476"
],
"cna_assigner": "VulnCheck"
}{
"extracted_events": [
{
"introduced": "0"
},
{
"last_affected": "3.4.0"
}
],
"source": [
"CPE_RANGE",
"REFERENCES"
],
"cpe": "cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*"
}