Summary
c3p0 can, in combination with other libraries, compose to a "sink" for deserialization gadgets
Workarounds
If users can ensure the safety of all JDBC drivers on the application CLASSPATH, or that no libraries lie on the CLASSPATH that can be composed to trigger automatic JavaBean property lookups on deserialization, then this attack is prevented. Nevertheless, given the complexity of modern JDBC drivers and typical Java application transitive dependencies, it is strongly recommended that users upgrade to c3p0 version 0.14.0 or higher.
Some versions of this attack are foiled by the stronger encapsulation and restriction of reflective access introduced in Java 16. Running applications on Java 16+ is therefore a potential mitigation.
This attack is described by Hans-Martin Münch in a blog post called "Look Mama, no TemplatesImpl".
Impact
The JDBC spec defines the interface DataSource, with a method called getConnection(), and ConnectionPoolDataSource, with a method called getPooledConnection(). These methods are potentially dangerous. One way or another they trigger calls into JDBC drivers, which themselves are complicated, flexible tools which may be, and in practice sometimes have proven to be, susceptible to abuse.
Unfortunately, the JavaBean framework treats methods of this form, getXXX(), as JavaBean "properties", which JavaBean-related libraries often presume represent quick, safe-to-look-up, state or configuration.
Attackers therefore can construct malicious DataSource objects, objects whose calls to getConnection() or getPooledConnection() would trigger attacks via vulnerable JDBC drivers, and bundle them in contexts that automatically look up bean properties on deserialization. If an attacker can smuggle such an object in serialized form to a location from which an application will deserialize it, an attack is triggered.
It's not easy. It requires that a susceptible JDBC DataSource or ConnectionPoolDataSource be available on the application CLASSPATH, along with a susceptible JDBC driver, and a carrier that will automatically look up JavaBean properties on deserialization. In practice, the most common such carrier is the composition of a collection and a Comparator implementation that sorts based on JavaBean properties from Apache commons-beanutils.
But c3p0 prior to 0.14.0 offered the susceptible JDBC DataSource or ConnectionPoolDataSource, supplying an essential component of the trigger.
Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.
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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c3p0 versions 0.14.0 and above no longer participate in this class of attack, because they include explicit BeanInfo classes which exclude connection and pooledConnection from the list of "introspected" JavaBean properties. Since getConnection() and getPooledConnection() no longer define JavaBean properties, classes that promiscuously read JavaBean properties do not call them, and the attack is averted.
Frequently Asked Questions
- What is CVE-2026-55223? CVE-2026-55223 is a medium-severity insecure deserialization vulnerability in com.mchange:c3p0 (maven), affecting versions < 0.14.0. It is fixed in 0.14.0. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
- Which versions of com.mchange:c3p0 are affected by CVE-2026-55223? com.mchange:c3p0 (maven) versions < 0.14.0 is affected.
- Is there a fix for CVE-2026-55223? Yes. CVE-2026-55223 is fixed in 0.14.0. Upgrade to this version or later.
- Is CVE-2026-55223 exploitable, and should I be worried? Whether CVE-2026-55223 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-2026-55223 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-2026-55223? Upgrade
com.mchange:c3p0to 0.14.0 or later.