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.

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.

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.

Affected products

Go-vikunja Vikunja

Weakness classification (CWE)

CWE-307 — Improper Restriction of Excessive Authentication Attempts

References

disclosure@vulncheck.com (vendor-advisory)
disclosure@vulncheck.com (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.