CVE-2026-56765

critical · 9.3

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.

9.3

CVSS

0.5%

EPSS (exploit prob.)

43rd

EPSS percentile

2026-07-10

Published

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Weaknesses

CWE-639

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

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-56765