libevent — security advisory

{
  "id": "35cc72eb1eb95fc91e7ef1cee241784b9ec64fa1f8ca3955770441c07a729f6c",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-63379",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-63379",
    "summary": "Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked HTTP trailers in http.c through evhttp_read_trailer and merges them into request headers. The fix introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent application interpret different effective headers, enabling header smuggling, authorization bypass, proxy-header spoofing, or cache poisoning. The fix parses trailers into a temporary header list and discards them instead of merging them into req->input_headers. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.",
    "evidence": "osv:DEBIAN-CVE-2026-63379",
    "products": [
      {
        "name": {
          "value": "libevent",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.1.12-stable-8+deb12u1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.1.12-stable-8",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "libevent",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.1.13-stable-1~deb13u1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.1.12-stable-10",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "libevent",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.1.13-stable-1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.1.12-stable-10",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "2.1.13-stable-1~deb13u1",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2026-63379",
      "aliases": [
        "DEBIAN-CVE-2026-63379"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.1.12-stable-8+deb12u1"
                }
              ]
            }
          ],
          "package": {
            "name": "libevent",
            "purl": "pkg:deb/debian/libevent?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "versions": [
            "2.1.12-stable-8"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63379.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.1.13-stable-1~deb13u1"
                }
              ]
            }
          ],
          "package": {
            "name": "libevent",
            "purl": "pkg:deb/debian/libevent?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "versions": [
            "2.1.12-stable-10"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63379.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.1.13-stable-1"
                }
              ]
            }
          ],
          "package": {
            "name": "libevent",
            "purl": "pkg:deb/debian/libevent?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "versions": [
            "2.1.12-stable-10",
            "2.1.13-stable-1~deb13u1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63379.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-27T09:47:41.618963278Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-63379"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-63379"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-63379",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 461265,
  "published_at": "2026-08-20T18:16:35.2+00:00"
}