HAProxy - NULL Pointer Dereference in hpack_dht_insert Function

{
  "id": "69469c135244046e1e537281cabd281076e879eba4f1db8163903940697bd1d9",
  "url": "https://osv.dev/vulnerability/BIT-haproxy-2026-55204",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "HAProxy - NULL Pointer Dereference in hpack_dht_insert Function",
    "summary": "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.",
    "evidence": "osv:BIT-haproxy-2026-55204",
    "products": [
      {
        "name": {
          "value": "haproxy",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.4.36",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "2.6.30",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "2.8.25",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "3.0.24",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "3.2.20",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "3.4.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "BIT-haproxy-2026-55204",
      "aliases": [
        "BIT-haproxy-2026-55204",
        "CVE-2026-55204"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.4.36"
                },
                {
                  "introduced": "2.5.0"
                },
                {
                  "fixed": "2.6.30"
                },
                {
                  "introduced": "2.7.0"
                },
                {
                  "fixed": "2.8.25"
                },
                {
                  "introduced": "2.9.0"
                },
                {
                  "fixed": "3.0.24"
                },
                {
                  "introduced": "3.1.0"
                },
                {
                  "fixed": "3.2.20"
                },
                {
                  "introduced": "3.3.0"
                },
                {
                  "fixed": "3.4.1"
                }
              ]
            }
          ],
          "package": {
            "name": "haproxy",
            "purl": "pkg:bitnami/haproxy",
            "ecosystem": "Bitnami"
          },
          "severity": [
            {
              "type": "CVSS_V4",
              "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
            }
          ],
          "database_specific": {
            "source": "https://github.com/bitnami/vulndb/tree/main/data/haproxy/BIT-haproxy-2026-55204.json"
          }
        }
      ],
      "modified": "2026-10-09T12:00:08.136016362Z",
      "provider": "osv",
      "references": [
        "https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-55204",
        "https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function"
      ],
      "provider_metadata": {
        "cpes": [
          "cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*"
        ],
        "severity": "High"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-55204",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 120656,
  "published_at": "2026-06-29T05:40:50.508+00:00"
}