CVE-2026-56765 Vikunja: Unauthenticated Instance-Wide Data Breach via Link Share Hash Disclosure Chained with Cross-Project Attachment IDOR
Attackers can exploit authorization flaws to read share hashes and access or delete attachments across all projects without proper ownership verification.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-56765?
CVE-2026-56765 is a critical missing authorization vulnerability in Vikunja, published on 10 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-639
Which versions are affected by CVE-2026-56765?
3 open source packages ship an affected version, including code.vikunja.io/api.
| Package | Affected | Fixed in |
|---|---|---|
code.vikunja.io/api Go | All versions | None |
code.vikunja.io/api Go | All versions | 2.2.1 |
code.vikunja.io/api Go | All versions | 2.2.1 |
How do I fix CVE-2026-56765?
Upgrade code.vikunja.io/api to 2.2.1 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-56765 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-56765 exists.
Sources
Also known as GHSA-2pv8-4c52-mf8j, GHSA-pg6g-jf8c-49p7, GO-2026-4855.