EUVD-2026-27424CVSS VectorNVD
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
4DescriptionNVD
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.
AnalysisAI
Vaultwarden versions 1.35.4 and earlier allow authenticated attackers to permanently disable WebAuthn two-factor authentication for user credentials by exploiting a logic flaw in the validate_webauthn_login() function that updates backup eligibility flags before validating the WebAuthn signature. An attacker with knowledge of a user's password can modify these persistent flags even when providing an invalid WebAuthn signature, causing signature verification to fail without rolling back the database changes, resulting in denial of service of the 2FA mechanism for affected credentials. …
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External POC / Exploit Code
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