Summary
c3p0 vulnerable to Remote Code Execution via unsafe deserialization of userOverridesAsString property
Workarounds
Users should upgrade to c3p0-0.12.0 or above. There is no supported workaround for earlier versions of c3p0.
References
c3p0, you little rascal — Hans-Martin Münch
c3p0 documentation, security note
c3p0 documentation, configuring security
Impact
c3p0 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.
Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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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. Those parameters are documented here.
c3p0 additionally enforces the new mchange-commons-java com.mchange.v2.naming.nameGuardClassName to prevent injection of unexpected, potentially remote JNDI names.
Frequently Asked Questions
- What is CVE-2026-27830? CVE-2026-27830 is a high-severity code injection vulnerability in com.mchange:c3p0 (maven), affecting versions < 0.12.0. It is fixed in 0.12.0. Untrusted input is evaluated as executable code within the application's runtime environment.
- Which versions of com.mchange:c3p0 are affected by CVE-2026-27830? com.mchange:c3p0 (maven) versions < 0.12.0 is affected.
- Is there a fix for CVE-2026-27830? Yes. CVE-2026-27830 is fixed in 0.12.0. Upgrade to this version or later.
- Is CVE-2026-27830 exploitable, and should I be worried? Whether CVE-2026-27830 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-27830 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-27830? Upgrade
com.mchange:c3p0to 0.12.0 or later.