CVE-2026-91972: Vikunja before 2.6.0 Authentication Bypass via Unthrottled API

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-15 · updated 2026-09-17
Weakness: CWE-307

Description

Vikunja versions before 2.6.0 fail to apply rate limiting to /api/v2 public authentication endpoints including login, register, password-reset, and OAuth token routes. Remote unauthenticated attackers can perform unbounded credential guessing, account enumeration, and password-reset flooding attacks without throttling restrictions.

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-6rvj-qwjf-3m4q
https://www.vulncheck.com/advisories/vikunja-before-2.6.0-authentication-bypass-via-unthrottled-api
https://github.com/go-vikunja/vikunja/security/advisories/GHSA-6rvj-qwjf-3m4q

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