{"id":"CVE-2026-91981","title":"Vikunja versions before 2.6.0 fail to properly validate link-share tokens in the v2 API user search endpoints","summary":"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 ex…","severity":"medium","cvss":4.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","cwe":["CWE-200"],"vendor":"go-vikunja","product":"vikunja","affected":["vikunja < 2.6.0"],"published":"2026-09-15","updated":"2026-09-21","sourceUpdated":"2026-09-21T19:17:16.220","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-91981","references":[{"url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vfxw-3x8p-2vjr","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/vikunja-before-2.6.0-user-enumeration-via-v2-api","label":"disclosure@vulncheck.com"},{"url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vfxw-3x8p-2vjr","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd","cve.org","exploit-available"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-21T18:47:21.313184Z"},"epss":0.00241,"epssPercentile":0.155,"ingestedAt":"2026-09-15T15:39:12.911Z","slug":"CVE-2026-91981","body":"## Overview\n\nVikunja 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":36,"depthScoreParts":{"impact":23.7,"likelihood":0,"exploitation":12,"ransomware":0},"changes":[{"seq":208753,"id":"CVE-2026-91981","ts":1790020353561,"field":"exploit_available","old":"false","new":"true"}]}