Affected: HubSpot jinjava

JinJava is a Java-based template engine based on django template syntax, adapted to render jinja templates. Prior to versions 2.7.6 and 2.8.3, JinJava is vulnerable to arbitrary Java execution via bypass through ForTag. This allows arbitrary Java class instantiation and file access bypassing built-in sandbox restrictions. This issue has been patched in versions 2.7.6 and 2.8.3.

Affected: Maven: com.hubspot.jinjava:jinjava

## Impact

**Vulnerability Type**: Sandbox Bypass / Remote Code Execution

**Affected Component**: Jinjava

**Affected Users**: - Organizations using HubSpot's Jinjava template rendering engine for user-provided template content - Any system that renders untrusted Jinja templates using HubSpot's Jinjava implementation - Users with the ability to create or edit custom code templates

**Severity**: **Critical** - allows arbitrary Java class instantiation and file access bypassing built-in sandbox restrictions

**Root Cause**: Multiple security bypass vulnerabilities in Jinjava's sandbox mechanism:

1. **ForTag Property Access Bypass**: The `ForTag` class does not enforce `JinjavaBeanELResolver` restrictions when iterating over object properties using `Introspector.getBeanInfo()` and invoking getter methods via `PropertyDescriptor.getReadMethod()`

2. **Restricted Class Instantiation**: The sandbox's type allowlist can be bypassed by using ObjectMapper to instantiate classes through JSON deserialization, including creating new `JinjavaELContext` and `JinjavaConfig` instances

**Attack Vector**: An attacker with the ability to create or edit Jinja templates can: - Access arbitrary getter methods on objects in the template context - Instantiate `ObjectMapper` to enable default typing - Create arbitrary Java classes by bypassing type allowlists - Read files from the server filesystem (demonstrated with `/etc/passwd`) - Potentially execute arbitrary code

## Patches

**Status**: Pa…