JinJava Bypass through ForTag leads to Arbitrary Java Execution

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-25526: 0.97% estimated exploitation activity in the next 30 days; percentile 61.76 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

3 Feb 2026, 17:52 UTC

Last modified by the source

5 Feb 2026, 00:35 UTC

Source last checked

26 Oct 2026, 16:44 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-gjx9-j8f8-7j74

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# Patch Next advisory brief: CVE-2026-25526

Advisory: JinJava Bypass through ForTag leads to Arbitrary Java Execution
IDs: CVE-2026-25526, GHSA-gjx9-j8f8-7j74
Record: https://patchnext.com/advisories/cve-2026-25526 (revision 1, source checked 26 Oct 2026, 16:44 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: com.hubspot.jinjava:jinjava 2.8.3, 2.7.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven com.hubspot.jinjava:jinjava: affected >= 2.8.0, < 2.8.3; < 2.7.6; fixed in 2.7.6, 2.8.3

## Suggested inspection (read-only)
- Maven com.hubspot.jinjava:jinjava: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on com.hubspot.jinjava:jinjava.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-gjx9-j8f8-7j74 (GitHub-reviewed advisory GHSA-gjx9-j8f8-7j74 lists affected ranges: Maven com.hubspot.jinjava:jinjava >=2.8.0 =0 <2.7.6)

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