CVE-2026-56765

EUVD-2026-42890

10.07.2026, 15:16

Vikunja before 2.2.1 contains an authorization flaw where the LinkSharing.ReadAll endpoint exposes share hashes to users with read access, enabling permission escalation to admin-level shares. The GetTaskAttachment endpoint performs permission checks against user-supplied task IDs but fetches attachments by sequential ID without verifying ownership, allowing attackers to download and delete all file attachments across all projects instance-wide.

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
VulnCheck	CNA	9.8 CRITICAL	NETWORK	LOW	NONE	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Base Score

CVSS 3.x

EPSS Score

Percentile: Unknown

Early Detection

Affected products identified ahead of NVD analysis through intelligence sources.

Vendor	Product	Version	Source
vikunja	vikunja	𝑥 < 2.2.1	CNA

Common Weakness Enumeration

CWE-639 - Authorization Bypass Through User-Controlled Key
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.

References

https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2pv8-4c52-mf8j

https://www.vulncheck.com/advisories/vikunja-unauthenticated-instance-wide-data-breach-via-link-share-hash-disclosure-chained-with-cross-project-attachment-idor

https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2pv8-4c52-mf8j