Apereo CAS Groovy Code RegisteredServiceSimpleFormController.java saveService code injection

Vulnerability

Overview

CVE-2025-3984 is a critical code injection vulnerability affecting Apereo CAS version 5.2.6. The flaw resides in the saveService function of the RegisteredServiceSimpleFormController.java file within the Groovy Code Handler component [1]. The root cause allows an attacker to inject and execute arbitrary code through manipulation of this service-saving endpoint [1].

Exploitation

Details

The attack is remotely exploitable but requires high complexity, making exploitation difficult in practice [1]. According to the official description, the attack can be launched over the network, though specific prerequisites such as authentication requirements or necessary privileges were not detailed [1]. A proof-of-concept exploit has been publicly disclosed, increasing the risk that threat actors may incorporate it into their operations [1].

Impact

Successful exploitation could lead to full remote code execution within the context of the CAS server. This could allow an attacker to compromise the underlying system, access sensitive user data, bypass authentication, or pivot to internal networks [1]. Given that CAS is used as a central identity provider (Single Sign-On), such a breach could have widespread consequences for affected organizations [2].

Mitigation

Status

The vendor, Apereo, was contacted about the vulnerability but did not respond, and no official patch or advisory has been released as of the publication date [1]. Organizations running Apereo CAS 5.2.6 should consider isolating the affected instance, applying strict network access controls, and monitoring for exploitation attempts. Users are strongly urged to upgrade to a supported, patched version of CAS (such as a later release) as soon as possible, or implement a Web Application Firewall (WAF) rule to block malicious payloads targeting the saveService endpoint [2].