CVE-2026-31835: Dani-Garcia Vaultwarden

Medium severity, CVSS 5.4. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Dani-Garcia Vaultwarden: before 1.35.5 (fixed in 1.35.5)

Published 2026-05-05. Last modified 2026-07-25.