CVE-2026-27830

c3p0, a JDBC Connection pooling library, is vulnerable to attack via maliciously crafted Java-serialized objects and `javax.naming.Reference` instances. Several c3p0 `ConnectionPoolDataSource` implementations have a property called `userOverridesAsString` which conceptually represents a `Map<String,Map<String,String>>`. Prior to v0.12.0, that property was maintained as a hex-encoded serialized object. Any attacker able to reset this property, on an existing `ConnectionPoolDataSource` or via maliciously crafted serialized objects or `javax.naming.Reference` instances could be tailored execute unexpected code on the application's `CLASSPATH`. The danger of this vulnerability was strongly magnified by vulnerabilities in c3p0's main dependency, mchange-commons-java. This library includes code that mirrors early implementations of JNDI functionality, including ungated support for remote `factoryClassLocation` values. Attackers could set c3p0's `userOverridesAsString` hex-encoded serialized objects that include objects "indirectly serialized" via JNDI references. Deserialization of those objects and dereferencing of the embedded `javax.naming.Reference` objects could provoke download and execution of malicious code from a remote `factoryClassLocation`. Although hazard presented by c3p0's vulnerabilites are exarcerbated by vulnerabilities in mchange-commons-java, use of Java-serialized-object hex as the format for a writable Java-Bean property, of objects that may be exposed across JNDI interfaces, represents a serious independent fragility. The `userOverridesAsString` property of c3p0 `ConnectionPoolDataSource` classes has been reimplemented to use a safe CSV-based format, rather than rely upon potentially dangerous Java object deserialization. c3p0-0.12.0+ and above depend upon mchange-commons-java 0.4.0+, which gates support for remote `factoryClassLocation` values by configuration parameters that default to restrictive values. c3p0 additionally enforces the new mchange-commons-java `com.mchange.v2.naming.nameGuardClassName` to prevent injection of unexpected, potentially remote JNDI names. There is no supported workaround for versions of c3p0 prior to 0.12.0.

• github.comhttps://github.com/swaldman/c3p0/commit/e14cbd8166e423e2e9a9d6f08b2add3433492d6e
• github.comhttps://github.com/swaldman/c3p0/security/advisories/GHSA-5476-xc4j-rqcv
• mogwailabs.dehttps://mogwailabs.de/en/blog/2025/02/c3p0-you-little-rascal
• www.mchange.comhttps://www.mchange.com/projects/c3p0/#configuring_security
• www.mchange.comhttps://www.mchange.com/projects/c3p0/#security-note
• access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:18054
• access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:18055
• access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:18059
• access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:28385
• access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:3890
• access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:4285
• access.redhat.comhttps://access.redhat.com/security/cve/CVE-2026-27830
• bugzilla.redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2442908
• security.access.redhat.comhttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27830.json