CVE-2026-31835

Published May 5, 2026

Last updated 2 months ago

CVSS medium 5.3

Overview

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
security-advisories@github.com
NVD status
Analyzed
Products
vaultwarden

Risk scores

CVSS 4.0

Type
Secondary
Base score
5.3
Impact score
-
Exploitability score
-
Vector string
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
Severity
MEDIUM

CVSS 3.1

Type
Primary
Base score
5.4
Impact score
2.5
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
Severity
MEDIUM

Weaknesses

security-advisories@github.com
CWE-345

Social media

Hype score
Not currently trending

Configurations

Related CVEs

  1. Vaultwarden is a Bitwarden-compatible server written in Rust. Prior to 1.35.5, Vaultwarden allows an unconfirmed organization owner to purge the entire organization vault. The organization invite flow uses a two-step process: accepting an invite transitions membership from Invited to Accepted, and a separate confirmation by an existing owner upgrades it to Confirmed. The POST /api/ciphers/purge endpoint uses plain Headers and only checks that the membership type is Owner without verifying that the membership status is Confirmed. An authenticated user who has been invited as an organization owner and has accepted the invite and has not yet been confirmed can call this endpoint to hard-delete all ciphers and attachments in the organization, causing immediate organization-wide data loss. This vulnerability is fixed in 1.35.5.•CVE-2026-43913
  2. Vaultwarden is a Bitwarden-compatible server written in Rust. Prior to 1.35.4, there is a security vulnerability in Vaultwarden that allows bypassing the login brute-force protection if email 2fa is enabled. If email 2fa is enabled, the unprotected 2fa-function send_email_login (email.rs, api endpoint /api/two-factor/send-email-login) also acts as an oracle determining whether a username-password combination is correct. An attacker can abuse that endpoint to brute-force passwords without rate-limiting. This works even for users who don't have email 2fa configured. This vulnerability is fixed in 1.35.4.•CVE-2026-43914
  3. Vaultwarden is a Bitwarden-compatible server written in Rust. Prior to 1.35.5, refresh tokens are not invalidated when the user's security_stamp is rotated by some security-sensitive operations (password change, KDF change, key rotation, email change, org admin password reset, emergency access takeover). This allows an attacker holding a previously obtained refresh token to maintain session access even after the user has taken action to secure their account. This vulnerability is fixed in 1.35.5.•CVE-2026-43911
  4. Vaultwarden is a Bitwarden-compatible server written in Rust. Prior to 1.35.5, Vaultwarden does not enforce that a groups_users.users_organizations_uuid entry belongs to the same organization as groups.groups_uuid, or a collections_groups.collections_uuid entry belongs to the same organization as collections_groups.groups_uuid. Multiple organization group-management endpoints accept arbitrary MembershipId and CollectionId values and persist them directly without verifying org consistency. This lets an attacker who is Admin in Organization A, and only a low-privileged member in Organization B bind their Org B membership UUID into an Org A group, then use that foreign group relationship to gain unauthorized access to Org B vault data. With an accessAll=true Org A group, the attacker can make /api/sync and /api/ciphers enumerate Org B ciphers. Once those unauthorized sync results reveal Org B collection IDs, the attacker can also bind those foreign collection IDs to the Org A group and turn the same flaw into write access over Org B items. This vulnerability is fixed in 1.35.5.•CVE-2026-43912
  5. Vaultwarden is a Bitwarden-compatible server written in Rust. In version 1.35.4 and earlier, the get_org_collections_details endpoint (GET /api/organizations/{org_id}/collections/details) is missing the has_full_access() authorization check that exists on the sibling get_org_collections endpoint. This allows any Manager-role user with accessAll=False and no collection assignments to retrieve the names, UUIDs, user-to-collection mappings, and group-to-collection mappings for all collections in the organization. This issue has been fixed in version 1.35.5.•CVE-2026-33420

References

Sources include official advisories and independent security research.