Vikunja: CalDAV relation creation bypasses TaskRelation.CanCreate, allowing an unauthorized write into any task by known UID — GHSA-G38J-7V97-X298

Summary

### Summary Creating a task relation over CalDAV does not run the `TaskRelation.CanCreate` permission check that the REST API enforces. An attacker can attach a relation to any task whose UID they know, including tasks in projects they have no access to. The identical operation over REST is correctly refused with 403. ### Details `persistRelations` (`pkg/routes/caldav/listStorageProvider.go`, ~line 986) resolves…

Timeline

Published by source

2026-10-09

Risk context

• Reported severity or threat level: medium.
• Reported CVSS score: 6.3 out of 10.
• Review exposure for the affected product or family: go: code.vikunja.io/api.

Product

go: code.vikunja.io/api

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source

Evidence and provenance

Canonical advisory ID

GHSA-G38J-7V97-X298

Source

GitHub

Vendor

GitHub

Published by source

2026-10-09

Last source activity

2026-10-09

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.