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Ubuntu Security Notice USN-6913-2
July 31, 2024

php-cas vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 LTS

Summary:

phpCAS was vulnerable to an authentication bypass.

Software Description:
- php-cas: Central Authentication Service client library in php

Details:

USN-6913-1 fixed CVE-2022-39369 for Ubuntu 20.04 LTS and Ubuntu 22.04 LTS.
This update provides the corresponding fix for Ubuntu 16.04 LTS.

Original advisory details:

Filip Hejsek discovered that phpCAS was using HTTP headers to determine
the service URL used to validate tickets. A remote attacker could
possibly use this issue to gain access to a victim's account on a
vulnerable CASified service.

This security update introduces an incompatible API change. After applying
this update, third party applications need to be modified to pass in an
additional service base URL argument when constructing the client class.

For more information please refer to the section
"Upgrading 1.5.0 -> 1.6.0" of the phpCAS upgrading document:

https://github.com/apereo/phpCAS/blob/master/docs/Upgrading

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 16.04 LTS
php-cas 1.3.3-2ubuntu1+esm1
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-6913-2
https://ubuntu.com/security/notices/USN-6913-1
CVE-2022-39369