Quick answers
- Is CVE-2026-123511 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-123511 being exploited in the wild.
- How severe is CVE-2026-123511?
- Medium severity, with a CVSS score of 4.3, published 8 November 2026.
- Which products and versions are affected?
- Vikunja before 2.7.1.
- Is there a fix for CVE-2026-123511?
- Yes: fixed in 2.7.1. Until then: Cap the number of relations processed per VTODO and deduplicate related UIDs before creating dummy tasks and relations. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-123511 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-123511?
- Check whether you run Vikunja 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: 2.7.1
Cap the number of relations processed per VTODO and deduplicate related UIDs before creating dummy tasks and relations.
Technical details
The vulnerability exists in the CalDAV VTODO parser which fails to cap the number of RELATED-TO properties processed per request. An authenticated attacker can send a single PUT request containing a VTODO with thousands of RELATED-TO entries pointing to unknown UIDs, causing the server to create a dummy task and relation for each entry without quota limits. This results in database bloat and event pipeline overload.
Affected products
- Vikunja Vikunja before 2.7.1
Timeline
- 2026-10-22: disclosed
- 2026-11-08: advisory