CVE-2025-59340

jinjava’s current sandbox restrictions prevent direct access to dangerous methods such as getClass(), and block instantiation of Class objects. However, these protections can be bypassed.

By using mapper.getTypeFactory().constructFromCanonical(), it is possible to instruct the underlying ObjectMapper to deserialize attacker-controlled input into arbitrary classes. This enables the creation of semi-arbitrary class instances without directly invoking restricted methods or class literals.

As a result, an attacker can escape the sandbox and instantiate classes such as java.net.URL, opening up the ability to access local files and URLs(e.g., file:///etc/passwd). With further chaining, this primitive can potentially lead to remote code execution (RCE).

Details

jinjava templates expose a built-in variable ____int3rpr3t3r____, which provides direct access to the jinjavaInterpreter instance.
This variable was previously abused and protections were added to prevent call method from JinjavaInterpreter instances (see Add interpreter to blacklist).
However, interacting with the properties of JinjavaInterpreter instances remains unrestricted.

From ____int3rpr3t3r____, it is possible to traverse to the config field, which exposes an ObjectMapper. By invoking readValue(String content, JavaType valueType) on this ObjectMapper, an attacker can instantiate arbitrary classes specified via JavaType.

Although jinjava explicitly restricts dangerous classes such as Class, ClassLoader, and so on inside JinjavaBeanELResolver, the JavaType class itself is not restricted.

As a result, an attacker can leverage JavaType construction (constructFromCanonical) to instantiate semi-arbitrary classes without directly calling restricted methods.

This allows sandbox escape and the creation of powerful primitives.

Escape the Jinjava sandbox and instantiate a wide range of classes using JavaType.
This capability can be used to read arbitrary files and to perform full read SSRF by creating network-related objects.
In certain environments, depending on the available classes, this primitive can even lead to complete remote code execution.

CVE-2025-59340 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.8.1, 2.7.5); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-59340? CVE-2025-59340 is a critical-severity security vulnerability in com.hubspot.jinjava:jinjava (maven), affecting versions = 2.8.0. It is fixed in 2.8.1, 2.7.5.
2. How severe is CVE-2025-59340? CVE-2025-59340 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of com.hubspot.jinjava:jinjava are affected by CVE-2025-59340? com.hubspot.jinjava:jinjava (maven) versions = 2.8.0 is affected.
4. Is there a fix for CVE-2025-59340? Yes. CVE-2025-59340 is fixed in 2.8.1, 2.7.5. Upgrade to this version or later.
5. Is CVE-2025-59340 exploitable, and should I be worried? Whether CVE-2025-59340 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
6. What actually determines whether CVE-2025-59340 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.
7. How do I fix CVE-2025-59340?
   • Upgrade com.hubspot.jinjava:jinjava to 2.8.1 or later
   • Upgrade com.hubspot.jinjava:jinjava to 2.7.5 or later