{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "2.6.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "DESCRIPTION"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "a4218eeb8fb3ada95e14a2331731524c9120d5bd"
            }
          ],
          "repo": "https://github.com/go-vikunja/vikunja",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-m469-88xx-8rx2"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-307"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91973.json"
  },
  "details": "Vikunja before 2.6.0 contains an authentication bypass vulnerability in CalDAV BasicAuth endpoints that lack rate limiting protection. Remote unauthenticated attackers can issue unbounded credential-guessing requests against /dav, /.well-known, and /feeds routes to bypass the instance's anti-brute-force controls and compromise password-only accounts.",
  "id": "CVE-2026-91973",
  "modified": "2026-09-18T03:31:00.022395128Z",
  "published": "2026-09-15T15:18:23.488Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91973.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-m469-88xx-8rx2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91973"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/vikunja-before-2.6.0-authentication-bypass-via-caldav-basicauth"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Vikunja before 2.6.0 Authentication Bypass via CalDAV BasicAuth"
}