CVE-2026-91968: vikunja before 2.6.0 Denial of Service via unbounded filter recursion

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 2026-09-16
Weakness: CWE-674

Description

vikunja versions before 2.6.0 contain a resource exhaustion vulnerability in the task-filter endpoint that accepts deeply nested filter expressions without recursion depth limits. Authenticated attackers can supply thousands of nested parentheses in the filter query parameter to exhaust memory and terminate the API process.

Affected products

go-vikunja vikunja: from 2.5.0 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-xxc3-xpmc-vmvr
https://www.vulncheck.com/advisories/vikunja-before-2.6.0-denial-of-service-via-unbounded-filter-recursion
https://github.com/go-vikunja/vikunja/security/advisories/GHSA-xxc3-xpmc-vmvr

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