CVE-2024-55603: Insufficient session invalidation in Kanboard

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2024-12-19 · updated 2026-06-17
Weakness: CWE-613

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.

Affected products

kanboard: before 1.2.43 — fixed in 1.2.43

How to fix

Upgrade to a fixed version: kanboard 1.2.43. Check the vendor advisory for mitigations.

References

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