What’s Vulnerable › Vulnerabilities

CVE-2026-91971: Vikunja before 2.6.0 Denial of Service via Avatar Upload

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-15 · updated 2026-09-21
• Weakness: CWE-400

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.

Affected products

• go-vikunja vikunja: before 2.6.0 — fixed in 2.6.0

How to fix

Upgrade to a fixed version: go-vikunja vikunja 2.6.0. Check the vendor advisory for mitigations.

References

• https://github.com/go-vikunja/vikunja/security/advisories/GHSA-4vh2-39rq-rq8j
• https://www.vulncheck.com/advisories/vikunja-before-2.6.0-denial-of-service-via-avatar-upload
• https://github.com/go-vikunja/vikunja/security/advisories/GHSA-4vh2-39rq-rq8j

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