Eclipse Jetty: Early return from the JASPIAuthenticator code can potentially no clear ThreadLocal variables

Description (as reported)

A security vulnerability has been identified in Jetty's JaspiAuthenticator.java.

The root cause is a failure to consistently clear authentication metadata stored in ThreadLocal during certain error or incomplete authentication flows. Specifically, after a GroupPrincipalCallback is persisted into the ThreadLocal, the authentication process may exit prematurely — before the ThreadLocal storage is cleared — if a mandatory CallerPrincipalCallback is missing or an exception occurs. This allows a subsequent, unprivileged user processed by the same worker thread to inherit these residual security roles, leading to Broken Access Control and Privilege Escalation.

See also attached PDF.

Impact

An unauthenticated user may gain ungrated privileges from a previous request (privilege escalation).

Patches

No patches yet.

Workarounds

Do not use Jetty's JASPI.