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CVE-2026-31835— Vaultwarden WebAuthn credential metadata tampered before signature verification

Quick assessment

Affected
dani-garcia vaultwarden
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Vaultwarden是Daniel García个人开发者的一个用 Rust 编写的 Bitwarden 服务器 API 的替代实现。 Vaultwarden 1.35.4及之前版本存在数据伪造问题漏洞，该漏洞源于WebAuthn认证流程中在签名验证前更新凭据元数据，可能导致WebAuthn双因素认证持久拒绝服务。

AI Predicted 5.9 Difficulty: Easy EPSS 0.19% · P8

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
dani-garcia vaultwarden < 1.35.5 affected
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I. Basic Information for CVE-2026-31835

Vulnerability Information
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Vulnerability Title
Vaultwarden WebAuthn credential metadata tampered before signature verification
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
对数据真实性的验证不充分
Source: CVE Program / CVE List V5
Vulnerability Title
Vaultwarden 数据伪造问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Vaultwarden是Daniel García个人开发者的一个用 Rust 编写的 Bitwarden 服务器 API 的替代实现。 Vaultwarden 1.35.4及之前版本存在数据伪造问题漏洞，该漏洞源于WebAuthn认证流程中在签名验证前更新凭据元数据，可能导致WebAuthn双因素认证持久拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
dani-garcia vaultwarden < 1.35.5 -

II. Public POCs for CVE-2026-31835

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III. Intelligence Information for CVE-2026-31835

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Vendor Advisories for CVE-2026-31835 (1)

Vendor Pages for CVE-2026-31835 (1)

IV. Related Vulnerabilities

Same product: vaultwarden
Same vendor: dani-garcia
Same weakness: CWE-345

V. Comments for CVE-2026-31835

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