Vulnerability in Go-Vikunja Vikunja
CVE-2026-91973
Vikunja before 2.6.0 contains an authentication bypass vulnerability in CalDAV BasicAuth endpoints that lack rate limiting protection. Remote unauthenticated attackers can issue unbounded credential-guessing requests against /dav, /.well-known, and /feeds routes to bypass the instance's anti-brute-force controls and compromise password-only accounts.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.007 (52.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 52.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000
Affected products
Weakness classification (CWE)
References
- github.com/go-vikunja/vikunja/security/advisories/GHSA-m469-88xx-8rx2 (vendor-advisory)
- www.vulncheck.com/advisories/vikunja-before-2.6.0-authentication-bypass-via-cal… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-91973?
- CVE-2026-91973 is a high-severity vulnerability in Go-Vikunja Vikunja, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 7.5/10. Published 2026-09-15.
- How severe is CVE-2026-91973?
- High severity. CVSS v3 base score is 7.5 out of 10.