authentik has a forward authentication bypass with broken cookie

{
  "id": "abd355169b5117e37ec22660a4552c87e80a7e2b09df18a9e4e57a2c6492c357",
  "url": "https://osv.dev/vulnerability/CVE-2026-25748",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "authentik has a forward authentication bypass with broken cookie",
    "summary": "authentik is an open-source identity provider. Prior to 2025.10.4 and 2025.12.4, with a malformed cookie it was possible to bypass authentication when using forward authentication in the authentik Proxy Provider when used in conjunction with Traefik or Caddy as reverse proxy. When a malicious cookie was used, none of the authentik-specific X-Authentik-* headers were set which depending on application can grant access to an attacker. authentik 2025.10.4 and 2025.12.4 fix this issue.",
    "evidence": "osv:CVE-2026-25748",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-25748",
      "aliases": [
        "BIT-authentik-2026-25748",
        "CVE-2026-25748",
        "GHSA-fj56-5763-j8pp"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/goauthentik/authentik",
              "type": "GIT",
              "events": [
                {
                  "introduced": "6d1c7f90e2da9c2c4bc27a6c8784c4130e6fe822"
                },
                {
                  "fixed": "7b0f19465b64905b49357e10dc15abffec3737d0"
                },
                {
                  "fixed": "19ad8d3ae3f266ec1096bc4461fdf6bcda1aa079"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "2025.10.0-rc1"
                      },
                      {
                        "fixed": "2025.10.4"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "2025.10.0-rc1"
                      },
                      {
                        "fixed": "2025.12.4"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  }
                ]
              }
            }
          ],
          "versions": [
            "version/2025.10.3",
            "version/2025.10.2",
            "version/2025.10.1",
            "version/2025.10.0",
            "version/2025.10.0-rc3",
            "version/2025.10.0-rc2",
            "version/2025.10.0-rc1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-25748.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:32.962802028Z",
      "provider": "osv",
      "references": [
        "https://github.com/goauthentik/authentik/releases/tag/version%2F2025.10.4",
        "https://github.com/goauthentik/authentik/releases/tag/version%2F2025.12.4",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25748.json",
        "https://github.com/goauthentik/authentik/security/advisories/GHSA-fj56-5763-j8pp",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-25748"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-287"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25748.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-25748",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 499993,
  "published_at": "2026-02-12T19:36:45.631+00:00"
}