CVE-2026-91971 Vikunja before 2.6.0 Denial of Service via Avatar Upload
Authenticated users can cause denial of service by uploading crafted images that consume excessive CPU and memory during processing.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-91971?
CVE-2026-91971 is a high-severity denial of service vulnerability in go-vikunja vikunja, published on 15 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Vikunja before 2.6.0 fails to apply pixel decode limits to avatar and project-background upload endpoints, allowing authenticated users to upload crafted images that decode to excessive pixel counts. Attackers can upload small images with extreme aspect ratios that consume significant CPU and memory during processing, causing denial of service through repeated or concurrent uploads.
Weakness: CWE-400
Which versions are affected by CVE-2026-91971?
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 | 2.6.0 |
code.vikunja.io/api Go | All versions | 2.6.0 |
How do I fix CVE-2026-91971?
Upgrade code.vikunja.io/api to 2.6.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-91971 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-91971 exists.
Sources
Also known as GHSA-4vh2-39rq-rq8j, GO-2026-6717.