CVE-2025-59340 is a critical-severity (CVSS 9.8) CWE-1336 vulnerability in com.hubspot.jinjava:jinjava. A fix is available for com.hubspot.jinjava:jinjava — see the affected versions and patch details below.
jinjava Sandbox Bypass via JavaType-Based Deserialization
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-59340.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
com.hubspot.jinjava:jinjava☕com.hubspot.jinjava:jinjavaReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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.
Impact
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.hubspot.jinjava:jinjava | ≥ 2.8.0&&< 2.8.1 | 2.8.1com.hubspot.jinjava:jinjava:2.8.1 |
| ☕Maven | com.hubspot.jinjava:jinjava | ≥ 2.7.0&&< 2.7.5 | 2.7.5com.hubspot.jinjava:jinjava:2.7.5 |
Affected Products
jinjavahubspotDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.hubspot.jinjava:jinjava, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.hubspot.jinjava:jinjava to 2.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-59340 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Frequently Asked Questions
Is CVE-2025-59340 in your dependencies?
Find it across Maven, including transitive dependencies.