{
  "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-vfxw-3x8p-2vjr"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-200"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91981.json"
  },
  "details": "Vikunja versions before 2.6.0 fail to properly validate link-share tokens in the v2 API user search endpoints. Attackers with a read-only share link can enumerate project users via the projects endpoint and confirm arbitrary usernames exist via the global search endpoint.",
  "id": "CVE-2026-91981",
  "modified": "2026-09-18T03:30:51.546702550Z",
  "published": "2026-09-15T15:18:25.523Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91981.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vfxw-3x8p-2vjr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91981"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/vikunja-before-2.6.0-user-enumeration-via-v2-api"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Vikunja before 2.6.0 User Enumeration via v2 API"
}