CAS OpenID Connect Vulnerability Disclosure


Overview

This is the version of an Apereo CAS project vulnerability disclosure, describing an issue in CAS that when it’s acting as an OAuth OR OpenID Connect identity provider. If you are not using CAS as an OAuth OR OpenID Connect Provider, there is nothing to do here. Keep calm and carry on.

For additional details on how security issues, patches and announcements are handled, please read the Apereo CAS project vulnerability disclosure process.

Affected Deployments

The security issue described here, per the CAS maintenance policy, affects the Apereo CAS server for the following versions:

- 6.4.x
- 6.5.x

If your CAS version is not listed above AND is still part of an active maintenance cycle per the CAS maintenance policy, then best effort (analysis or confirmation from reporters/testers) indicates that the version is not affected by this issue. That said, please note that per the project’s Apache2 license, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.. For additional information, please see the project license.

If you or your institution is a member of the Apereo foundation with an active support subscription supporting the CAS project, please contact the CAS subs working group to learn more about this security vulnerability report.

Severity

When CAS is acting as an OAuth OR OpenID Connect identity provider, the underlying issue allows an attacker to bypass the CAS service registry and application registrations by crafting a special URL and ultimately force CAS to receive a service ticket for an unauthorized application that is capable of understanding the CAS protocol.

Timeline

The issue was originally reported on May 19th, 2022 and upon confirmation, CAS releases were patched on May 25th, 2022, and June 23rd 2022.

Patching

Patch releases are available to address CAS deployments. Upgrades to the next patch version for each release should be a drop-in replacement.

Procedure

6.4.x

Modify your CAS overlay to point to the version 6.4.6.4.

6.5.x

Modify your CAS overlay to point to the version 6.5.5.

Support

Apereo CAS is Apache v2 open source software under the sponsorship of the Apereo Foundation, supported by community volunteers and enthusiasts. Support options may be found here.

If you or your institution is a member of the Apereo foundation with an active subscription supporting the CAS project, please contact the CAS subs working group to learn more about this security vulnerability report.

Resources

On behalf of the CAS Application Security working group,

Misagh Moayyed

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