CVE-2026-82843: WP OAuth Server < 6.4.0 - Subscriber+ Cross-User Account Takeover via OIDC ID Token Substitution
The WP OAuth Server ( Login with WordPress ) WordPress plugin before 6.4.0 does not bind the OpenID Connect identity assertion it issues to the authorization grant being exchanged, returning instead the assertion belonging to whichever user authenticated most recently, which allows users with the Subscriber role and above to obtain a validly signed identity assertion for another user, including an administrator, and authenticate as them at any application that uses the site for single sign-on.
Affected Software
Event History
Frequently Asked Questions
Which environments are exposed to downstream account impersonation?
Any application that relies on the affected WordPress site for single sign-on can accept the substituted identity assertion and authenticate the attacker as the other user. The impacted user can include an administrator.
What access does an attacker need?
The attacker needs a WordPress account with the Subscriber role or higher. They can obtain a validly signed identity assertion for whichever user authenticated most recently.
Can a relying application detect the forged identity by validating the token signature?
No. The substituted assertion is described as validly signed, so signature validation alone will not distinguish it from an assertion issued for the correct authorization grant.