Description

Kanboard is project management software that focuses on the Kanban methodology. In affected versions sessions are still usable even though their lifetime has exceeded. Kanboard implements a cutom session handler (`app/Core/Session/SessionHandler.php`), to store the session data in a database. Therefore, when a `session_id` is given, kanboard queries the data from the `sessions` sql table. At this point, it does not correctly verify, if a given `session_id` has already exceeded its lifetime (`expires_at`). Thus, a session which's lifetime is already `> time()`, is still queried from the database and hence a valid login. The implemented **SessionHandlerInterface::gc** function, that does remove invalid sessions, is called only **with a certain probability** (_Cleans up expired sessions. Called by `session_start()`, based on `session.gc_divisor`, `session.gc_probability` and `session.gc_maxlifetime` settings_) accordingly to the php documentation. In the official Kanboard docker image these values default to: session.gc_probability=1, session.gc_divisor=1000. Thus, an expired session is only terminated with probability 1/1000. This issue has been addressed in release 1.2.43 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

Weaknesses 1

Affected Products 1

References 8

• github.com https://github.com/kanboard/kanboard/blob/main/app/Core/Session/SessionHandler.php#L40
  Product
• github.com https://github.com/kanboard/kanboard/commit/7ce61c34d962ca8b5dce776289ddf4b207be6e78
  Patch
• github.com https://github.com/kanboard/kanboard/security/advisories/GHSA-gv5c-8pxr-p484
  ExploitVendor Advisory
• php.net https://www.php.net/manual/en/function.session-start.php
  Product
• php.net https://www.php.net/manual/en/session.configuration.php#ini.session.gc-divisor
  Product
• php.net https://www.php.net/manual/en/session.configuration.php#ini.session.gc-maxlifetime
  Product
• php.net https://www.php.net/manual/en/session.configuration.php#ini.session.gc-probability
  Product
• php.net https://www.php.net/manual/en/sessionhandlerinterface.gc.php
  Product

Remediation

• github.com https://github.com/kanboard/kanboard/commit/7ce61c34d962ca8b5dce776289ddf4b207be6e78
  Patch