Vulnerability in Dani-Garcia Vaultwarden
CVE-2026-31835
Vaultwarden is a Bitwarden-compatible server written in Rust. In versions 1.35.4 and earlier, the WebAuthn authentication flow in `validate_webauthn_login()` updates persistent credential metadata (1backup_eligible1 and 1backup_state flags1) based on unverified `authenticatorData` before signature validation is performed. An attacker who knows a user's password but cannot produce a valid WebAuthn signature can permanently modify the stored backup flags for that user's credential. If signature verification fails, the database update is not rolled back. This can result in a persistent denial of service of WebAuthn two-factor authentication for affected credentials. This issue has been fixed in version 1.35.5.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L.
EPSS exploit prediction
EPSS: 0.002 (4.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 4.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Dani-Garcia Vaultwarden — versions < 1.35.5
Weakness classification (CWE)
References
- github.com/dani-garcia/vaultwarden/security/advisories/GHSA-x7g7-cgx5-jhx2 (Exploit, Vendor Advisory)
- github.com/dani-garcia/vaultwarden/releases/tag/1.35.5 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-31835?
- CVE-2026-31835 is a medium-severity vulnerability in Dani-Garcia Vaultwarden, classified under Insufficient Verification of Data Authenticity. CVSS score: 5.4/10. Published 2026-05-05.
- How severe is CVE-2026-31835?
- Medium severity. CVSS v3 base score is 5.4 out of 10.