The partial-pipeline resume mechanism accepted partial token as a bearer credential without binding it to the browser session that created it.

Applications using resumable partial pipeline steps could allow an attacker to start an authentication flow, obtain a valid partial token and verification data, and cause a victim's browser to resume that attacker-controlled flow. This could authenticate the victim's browser as the attacker's account.

The issue affects applications using partial pipeline steps such as mail validation or custom steps decorated with @partial.

The issue has been fixed by binding partial pipeline resumes to the originating browser session.

Users should upgrade to a patched version.

Fix:

Applications that cannot upgrade immediately should disable resumable partial pipeline steps, including mail validation and custom steps decorated with @partial.

If those flows are required, applications should avoid accepting partial resume links from untrusted contexts until a patched version can be deployed.

There is no complete workaround while continuing to use the vulnerable partial-pipeline resume mechanism.

Reported through GitHub private vulnerability reporting by Liyi Zhou, Ziyue Wang, Strick, Maurice, and Chenchen Yu from the University of Sydney security research team.

Reporter references: