{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "2.6.0"
              },
              {
                "fixed": "3.3.6"
              }
            ],
            "source": [
              "CPE_RANGE",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "a1efc048bf8a5e14466dbe7317e73117e8d66176"
            },
            {
              "fixed": "d76ee72d03b088ad4616ff8bbee439798d5f18d6"
            },
            {
              "fixed": "05a295441c621089ffa4318daf0dbca2dd756a84"
            }
          ],
          "repo": "https://github.com/haproxy/haproxy",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "mitre",
    "cwe_ids": [
      "CWE-130"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33555.json"
  },
  "details": "An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.",
  "id": "CVE-2026-33555",
  "modified": "2026-08-12T03:51:18.209220047Z",
  "published": "2026-04-13T00:00:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html"
    },
    {
      "type": "WEB",
      "url": "https://www.haproxy.com/documentation/haproxy-aloha/changelog/"
    },
    {
      "type": "WEB",
      "url": "https://www.haproxy.org"
    },
    {
      "type": "WEB",
      "url": "https://www.mail-archive.com/haproxy@formilux.org/msg46752.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33555.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33555"
    },
    {
      "type": "FIX",
      "url": "https://github.com/haproxy/haproxy/commit/05a295441c621089ffa4318daf0dbca2dd756a84"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}