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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 4
https://github.com/go-vikunja/vikunja/commit/379d8a5c19334ffe4846003f590e202c31…
security-advisories@github.com
https://github.com/go-vikunja/vikunja/pull/2581
security-advisories@github.com
https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0
security-advisories@github.com
https://github.com/go-vikunja/vikunja/security/advisories/GHSA-96q5-xm3p-7m84
security-advisories@github.com