Authentication bypass in Alpine

Vulnerability Description

Alpine is a scaffolding library in Java. Alpine prior to version 1.10.4 allows Authentication Filter bypass. The AuthenticationFilter relies on the request URI to evaluate if the user is accessing the swagger endpoint. By accessing a URL with a path such as /api/foo;%2fapi%2fswagger the contains condition will hold and will return from the authentication filter without aborting the request. Note that the principal object will not be assigned and therefore the issue wont allow user impersonation. This issue has been fixed in version 1.10.4. There are no known workarounds.

References

• https://securitylab.github.com/advisories/GHSL-2021-1010-Alpine/
• https://github.com/stevespringett/Alpine/blob/f03dbda46229c26145a5f9f7f2660cc2c386be02/alpine/src/main/java/alpine/filters/AuthenticationFilter.java#L58-L60
• https://github.com/stevespringett/Alpine/releases/tag/alpine-parent-1.10.4