Medium severity · published Sep 15, 2026
CVE-2026-91971
Vikunja before 2.6.0 Denial of Service via Avatar Upload
6.5
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 38% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
VI
vikunja · go-vikunja
before 2.6.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-91971
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-91971
github.com
https://github.com/go-vikunja/vikunja/security/advisories/GHSA-4vh2-39rq-rq8j
www.vulncheck.com
https://www.vulncheck.com/advisories/vikunja-before-2.6.0-denial-of-service-via-avatar-upload
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