CVE-2026-91981 [MEDIUM] – Vikunja versions before 2.6.0 fail to properly validate link-share tokens in the v2 API us

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.