CVE-2026-91971
Received Received - Intake

Vikunja Avatar Image Pixel Denial of Service

Publication date: 2026-09-15

Last updated on: 2026-09-15

Assigner: VulnCheck

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.

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Meta Information

Published
2026-09-15
Last Modified
2026-09-15
Generated
2026-09-15
AI Q&A
2026-09-15
EPSS Evaluated
N/A
NVD
CVE-2026-91971
EUVD
EUVD-2026-78647

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
vikunja vikunja to 2.6.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.

Attack-Flow Graph

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Executive Summary

Vikunja before version 2.6.0 has a flaw where it does not enforce pixel limits on avatar and project-background image uploads. Attackers with valid accounts can upload small but extremely wide or tall images that require excessive CPU and memory to process. This leads to system overload and denial of service when multiple such uploads occur simultaneously.

Detection Guidance

Monitor for unusually high CPU or memory usage during image uploads, especially from authenticated users. Check server logs for repeated uploads of small images with extreme aspect ratios. No specific commands are provided in the context.

Impact Analysis

If you use Vikunja before 2.6.0, an attacker with access could upload malicious images to crash your server by consuming all available CPU and memory. This disrupts service for all users and may require manual intervention to restore normal operation.

Mitigation Strategies

Upgrade Vikunja to version 2.6.0 or later to apply pixel decode limits. Implement rate limiting on upload endpoints. Review and restrict user permissions to prevent unauthorized uploads. Monitor for suspicious activity.

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