CVE-2026-31835: CWE-345: Insufficient Verification of Data Authenticity in dani-garcia vaultwarden
Vaultwarden versions 1.35.4 and earlier contain a vulnerability in the WebAuthn authentication flow where persistent credential metadata flags are updated based on unverified authenticator data before signature validation. An attacker who knows a user's password but cannot produce a valid WebAuthn signature can modify these backup flags, causing a persistent denial of service for WebAuthn two-factor authentication on that user's credential. The issue is fixed in version 1.35.5.
AI Analysis
Technical Summary
In Vaultwarden (a Bitwarden-compatible server written in Rust), versions prior to 1.35.5 improperly update persistent credential metadata flags (1backup_eligible1 and 1backup_state1) during the WebAuthn login process before verifying the WebAuthn signature. This insufficient verification of data authenticity (CWE-345) allows an attacker with the user's password but without a valid WebAuthn signature to alter backup flags permanently. The database update is not rolled back if signature verification fails, leading to a persistent denial of service of WebAuthn two-factor authentication for affected credentials.
Potential Impact
An attacker who knows a user's password but cannot produce a valid WebAuthn signature can cause a persistent denial of service of WebAuthn two-factor authentication by modifying backup flags in the credential metadata. This undermines the availability of two-factor authentication for the affected user credentials, potentially weakening account security by forcing fallback to less secure authentication methods or lockout.
Mitigation Recommendations
This vulnerability has been fixed in Vaultwarden version 1.35.5. Users and administrators should upgrade to version 1.35.5 or later to remediate this issue. No other mitigation or workaround is indicated. Patch status is confirmed by the vendor's versioning information.
CVE-2026-31835: CWE-345: Insufficient Verification of Data Authenticity in dani-garcia vaultwarden
Description
Vaultwarden versions 1.35.4 and earlier contain a vulnerability in the WebAuthn authentication flow where persistent credential metadata flags are updated based on unverified authenticator data before signature validation. An attacker who knows a user's password but cannot produce a valid WebAuthn signature can modify these backup flags, causing a persistent denial of service for WebAuthn two-factor authentication on that user's credential. The issue is fixed in version 1.35.5.
CVSS v4.0
Score 5.3medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
In Vaultwarden (a Bitwarden-compatible server written in Rust), versions prior to 1.35.5 improperly update persistent credential metadata flags (1backup_eligible1 and 1backup_state1) during the WebAuthn login process before verifying the WebAuthn signature. This insufficient verification of data authenticity (CWE-345) allows an attacker with the user's password but without a valid WebAuthn signature to alter backup flags permanently. The database update is not rolled back if signature verification fails, leading to a persistent denial of service of WebAuthn two-factor authentication for affected credentials.
Potential Impact
An attacker who knows a user's password but cannot produce a valid WebAuthn signature can cause a persistent denial of service of WebAuthn two-factor authentication by modifying backup flags in the credential metadata. This undermines the availability of two-factor authentication for the affected user credentials, potentially weakening account security by forcing fallback to less secure authentication methods or lockout.
Mitigation Recommendations
This vulnerability has been fixed in Vaultwarden version 1.35.5. Users and administrators should upgrade to version 1.35.5 or later to remediate this issue. No other mitigation or workaround is indicated. Patch status is confirmed by the vendor's versioning information.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-09T17:41:56.078Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69fa3fb2cbff5d86101cd316
Added to database: 5/5/2026, 7:06:26 PM
Last enriched: 5/13/2026, 3:52:27 AM
Last updated: 6/20/2026, 7:33:48 AM
Views: 120
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.