Is This vulnerability exploited in the wild?

No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

How severe is This vulnerability?

Informational severity, published 19 October 2026.

Which products and versions are affected?

code.vikunja.io/api (Go) SEMVER:introduced=0; Vikunja API before 2.6.0.

Is there a fix for This vulnerability?

Yes: fixed in 2.6.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is This vulnerability attacked?

It is attacked over the network, in a software library.

Check whether you run code.vikunja.io/api (Go) or Vikunja API at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Vikunja CalDAV relation creation bypasses authorization

Severity: info · Published 2026-10-19

Vikunja is a task management and project planning application. An attacker with access to the CalDAV interface can create unauthorized task relations (subtask links) between tasks they control and any other task in the system if they know its unique identifier, even in projects they cannot access. This allows unauthorized modification of tasks and can enable information disclosure across project boundaries.

Technologies: code.vikunja.io/api (Go), Vikunja API. Vendors: Go, Vikunja.

Quick answers

Is This vulnerability exploited in the wild?: No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
How severe is This vulnerability?: Informational severity, published 19 October 2026.
Which products and versions are affected?: code.vikunja.io/api (Go) SEMVER:introduced=0; Vikunja API before 2.6.0.
Is there a fix for This vulnerability?: Yes: fixed in 2.6.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is This vulnerability attacked?: It is attacked over the network, in a software library.
Am I affected?: Check whether you run code.vikunja.io/api (Go) or Vikunja API at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: 2.6.0

Technical details

The CalDAV relation creation endpoint in persistRelations (caldav/listStorageProvider.go) bypasses the TaskRelation.CanCreate permission check that the REST API enforces, performing an unscoped UID lookup and directly calling rel.Create without authorization verification. An authenticated attacker can exploit this by submitting a RELATED-TO CalDAV property to attach relations to arbitrary tasks whose UID they know (leaked via CalDAV read access or retained after access revocation). The vulnerability requires authenticated access to CalDAV and knowledge of the victim task's UID.

Affected products

Vikunja api before 2.6.0

Identifiers

GHSA-g38j-7v97-x298
GO-2026-6732

Timeline

2026-08-31: disclosed
2026-10-19: patched

References

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