Security advisory

{
  "id": "3d066d047abde531f312a1d3986977cbdd0880384e4636689a4e6cc8256d9b37",
  "url": "https://osv.dev/vulnerability/CVE-2025-12642",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2025-12642",
    "summary": "lighttpd1.4.80 incorrectly merged trailer fields into headers after http request parsing. This behavior can be exploited to conduct HTTP Header Smuggling attacks. Successful exploitation may allow an attacker to: * Bypass access control rules * Inject unsafe input into backend logic that trusts request headers * Execute HTTP Request Smuggling attacks under some conditions This issue affects lighttpd1.4.80",
    "evidence": "osv:CVE-2025-12642",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2025-12642",
      "aliases": [
        "CVE-2025-12642"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/lighttpd/lighttpd1.4",
              "type": "GIT",
              "events": [
                {
                  "introduced": "b2bdd270506b4cad6a571b629e4fa0a01cd24631"
                },
                {
                  "last_affected": "b2bdd270506b4cad6a571b629e4fa0a01cd24631"
                },
                {
                  "fixed": "35cb89c103877de62d6b63d0804255475d77e5e1"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:lighttpd:lighttpd:1.4.80:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "1.4.80"
                      },
                      {
                        "last_affected": "1.4.80"
                      }
                    ],
                    "source": "CPE_STRING"
                  },
                  {
                    "range": [
                      {
                        "fixed": "35cb89c103877de62d6b63d0804255475d77e5e1"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.4.80",
            "lighttpd-1.4.80"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-12642.json",
            "vanir_signatures": [
              {
                "id": "CVE-2025-12642-473a78bc",
                "digest": {
                  "threshold": 0.9,
                  "line_hashes": [
                    "177279775846748800587473156359973412692",
                    "234107947651447384615462498936120486077",
                    "302025777481488930004506134913590170429",
                    "53861381006875801283685841489596921050"
                  ]
                },
                "source": "https://github.com/lighttpd/lighttpd1.4/commit/35cb89c103877de62d6b63d0804255475d77e5e1",
                "target": {
                  "file": "src/request.c"
                },
                "deprecated": false,
                "signature_type": "Line",
                "signature_version": "v1"
              }
            ],
            "vanir_signatures_modified": "2026-10-24T07:22:15Z"
          }
        }
      ],
      "modified": "2026-10-24T07:22:15.959447441Z",
      "provider": "osv",
      "references": [
        "https://github.com/lighttpd/lighttpd1.4/commit/35cb89c103877de62d6b63d0804255475d77e5e1"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2025-12642",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 428752,
  "published_at": "2025-11-03T20:17:06.41+00:00"
}