CVE-2026-91973

Summary

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.

Affected Software

VendorProductVersion RangeStatus
go-vikunjavikunja0 < 2.6.0affected
go-vikunjavikunja2.6.0unaffected

Weaknesses

  • CWE-307: Improper Restriction of Excessive Authentication Attempts

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: poc
    • Automatable: yes
    • Technical Impact: partial

Additional References

References