CVE-2026-79313: Pypi/web.py vulnerability
webpy web.py 0.76 is vulnerable to Insufficient Session Expiration. The application's session management relies on periodic cleanup to expire sessions instead of checking the last-access time when a session is loaded. As a result, an expired session whose record has not yet been cleaned up can still be replayed and used, allowing an attacker holding a previously valid session cookie to continue accessing protected resources after the configured idle timeout.
Affected Software
Event History
Frequently Asked Questions
What does an attacker need to exploit this issue?
An attacker needs a previously valid session cookie. They can replay it after the configured idle timeout if the corresponding session record has not yet been removed by periodic cleanup.
Are applications using the affected package exposed by default?
Exposure depends on the application using web.py session management and relying on its configured idle timeout to invalidate inactive sessions. The issue arises because expiration is enforced during periodic cleanup rather than when a session is loaded.
What can be done if patching is not immediately possible?
Reduce the window in which expired session records remain available by ensuring session cleanup runs frequently. Treat session cookies as potentially valid beyond the configured idle timeout until their server-side records have been removed.
How can I determine whether a session may still be usable after timing out?
Test whether a previously valid session cookie can still access protected resources after the configured idle timeout but before periodic session cleanup removes its server-side record. If it can, the application is affected by this behavior.