CVE-2026-91985 [HIGH] – Vikunja before 2.6.0 fails to properly restrict access to the link-share hash field in sin

Vikunja before 2.6.0 fails to properly restrict access to the link-share hash field in single-share read endpoints, allowing read-only members to obtain the share’s secret credential. Attackers can exchange the disclosed hash for a link-share JWT at the share’s permission level to escalate privileges and perform unauthorized writes or administrative actions.