CVE-2021-42567 Cross-site Scripting in Apereo CAS

What is CVE-2021-42567?

CVE-2021-42567 is a medium-severity cross-site scripting vulnerability in n/a, published on 7 Dec 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

Apereo CAS through 6.4.1 allows XSS via POST requests sent to the REST API endpoints.

Weakness: CWE-79

Which versions are affected by CVE-2021-42567?

2 open source packages ship an affected version, including org.apereo.cas:cas-server-core-web. It affects 1 product.

Products include Apereo Central Authentication Service.

How do I fix CVE-2021-42567?

Upgrade org.apereo.cas:cas-server-core-web to 6.4.2 or later.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2021-42567 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-42567 exists.

Public exploit code: 1 Nuclei template.

Other vulnerabilities in n/a

• CVE-2023-4612 MFA bypass in Apereo CAS Critical 9.8
• CVE-2024-4399 CAS <= 1.0.0 - Unauthenticated SSRF Critical 9.1
• CVE-2019-10754 Use of Insufficiently Random Values in Apereo CAS High 8.1
• CVE-2020-27178 Improper Authentication in Apereo CAS High 7.5
• CVE-2015-1169 Auth bypass in n/a High 7.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-gfhx-jjwq-63gv.