CVE-2026-35594: Vikunja Link Share JWT tokens remain valid for 72 hours after share deletion or permission downgrade

Vulnerability summary

CVE-2026-35594 is a medium (CVSS 6.5) Insufficient Session Expiration vulnerability in go-vikunja vikunja. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 37.3% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 10-04-2026
   PublishedVulnerability first disclosed.
2. 14-04-2026
   Last modifiedVulnerability information updated.

Description

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's link share authentication (GetLinkShareFromClaims in pkg/models/link_sharing.go) constructs authorization objects entirely from JWT claims without any server-side database validation. When a project owner deletes a link share or downgrades its permissions, all previously issued JWTs continue to grant the original permission level for up to 72 hours (the default service.jwtttl). This vulnerability is fixed in 2.3.0.

• CWE-613Insufficient Session ExpirationAccording to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization."