{"cve":"CVE-2026-91981","nvd":{"published":"2026-09-15T16:17:55.087","modified":"2026-09-21T19:17:16.220","status":"Deferred","description":"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.","cvss_v4":{"vector":"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","score":5.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","score":4.3},"cwes":["CWE-200"],"references":["https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vfxw-3x8p-2vjr","https://www.vulncheck.com/advisories/vikunja-before-2.6.0-user-enumeration-via-v2-api","https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vfxw-3x8p-2vjr"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:53:43.293028046+00:00"},"epss":{"cve":"CVE-2026-91981","score":0.00306,"percentile":0.2345,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-vfxw-3x8p-2vjr","url":"https://osv.dev/vulnerability/GHSA-vfxw-3x8p-2vjr","summary":"Vikunja: Link-share token can enumerate users through the v2 API","modified":"2026-10-19T21:40:54.809992875Z","packages":[{"ecosystem":"Go","name":"code.vikunja.io/api","purl":"pkg:golang/code.vikunja.io/api","ranges":["<2.6.0"],"fixed":["2.6.0"]}]},{"id":"GO-2026-6752","url":"https://osv.dev/vulnerability/GO-2026-6752","summary":"Vikunja: Link-share token can enumerate users through the v2 API in code.vikunja.io/api","modified":"2026-10-19T21:31:52.823927246Z","packages":[{"ecosystem":"Go","name":"code.vikunja.io/api","purl":"pkg:golang/code.vikunja.io/api","ranges":["all versions"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}