CVE-2026-76216
Received Received - Intake

Principal-Type Confusion in Vikunja

Publication date: 2026-08-19

Last updated on: 2026-08-19

Assigner: VulnCheck

Description
Vikunja through 2.4.0 contains a principal-type confusion vulnerability where LinkSharing principals with id N are treated as user principals with users.id == N at three permission checks lacking type guards. Attackers with a link-share JWT can remove victims from teams, enumerate and delete victim bot users, or read team rosters by exploiting id collisions in the autoincrement space.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-08-19
Last Modified
2026-08-19
Generated
2026-08-19
AI Q&A
2026-08-19
EPSS Evaluated
N/A
NVD
CVE-2026-76216
EUVD
EUVD-2026-62457

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
vikunja vikunja to 2.4.0 (inc)

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-639 The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

CVE-2026-76216 is a principal-type confusion vulnerability in Vikunja versions up to 2.4.0. It occurs when LinkSharing principals with an ID N are treated as user principals with users.id == N during permission checks. This flaw allows attackers with a link-share JWT to exploit ID collisions in the autoincrement space.

Detection Guidance

Check Vikunja version with: curl -s http://your-vikunja-server/api/v1/info | grep version. If version <= 2.4.0, the system is vulnerable. Review logs for unusual team membership changes, bot user deletions, or unauthorized roster access attempts.

Impact Analysis

Attackers can remove victims from teams, enumerate and delete victim bot users, or read team rosters. Exploitation requires link sharing to be enabled and relies on ID collisions. The vulnerability has a high severity rating with impacts on confidentiality, integrity, and availability.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, enabling attackers to read team rosters or delete bot users, which may violate GDPR's data protection requirements or HIPAA's confidentiality rules if personal or health data is exposed.

Mitigation Strategies

Upgrade Vikunja to version 2.4.1 or later immediately. Disable link sharing if not required. Audit team memberships and bot users for unauthorized changes. Monitor for suspicious JWT usage in link-sharing tokens.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-76216. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart