Executive brief
Vaultwarden, an open-source password management server, contains a security flaw in its Single Sign-On (SSO) login process. When a specific setting is enabled to link accounts by email address, the system fails to verify if the email address provided by the login provider has actually been verified. This could allow an attacker to create a malicious account on a third-party provider using a victim's email address and use it to take over the victim's existing password vault.
Technical details
An improper access control vulnerability exists in Vaultwarden's SSO implementation prior to version 1.36.0. When the configuration 'SSO_SIGNUPS_MATCH_EMAIL=true' is active, the server links incoming IdP identities to existing local accounts based on the email claim without checking the 'email_verified' status. An attacker who can control an IdP identity (or use an IdP that does not enforce email verification) can assert a victim's email address to bind to and authenticate as that local account. While the attacker would still need the Master Password to decrypt vault data, they can successfully authenticate to the account and fetch encrypted blobs. The fix in 1.36.0 ensures the 'email_verified' claim is validated during the account linking process.
Affected products
- dani-garcia Vaultwarden < 1.36.0
Timeline
- 2026-04-29: patched: Fixes merged into main branch via PR #7163
- 2026-05-03: advisory: Version 1.36.0 released with security fixes
- 2026-07-15: disclosed: CVE-2026-47164 published