CVE-2026-25526 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 Bypass through ForTag leads to Arbitrary Java Execution
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-2026-25526.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-25526 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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
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:
-
ForTag Property Access Bypass: The
ForTagclass does not enforceJinjavaBeanELResolverrestrictions when iterating over object properties usingIntrospector.getBeanInfo()and invoking getter methods viaPropertyDescriptor.getReadMethod() -
Restricted Class Instantiation: The sandbox's type allowlist can be bypassed by using ObjectMapper to instantiate classes through JSON deserialization, including creating new
JinjavaELContextandJinjavaConfiginstances
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
ObjectMapperto 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: Patched - CVE-2026-25526
Users should upgrade to one of the following versions which contain fixes for this vulnerability:
- JinJava 2.8.3 or later
- JinJava 2.7.6 or later
Fix Components:
-
ForTag Security Hardening
- Added security checks to
ForTag.renderForCollection()to enforceJinjavaBeanELResolverrestrictions - Implemented property access validation against restricted properties/methods before invoking getter methods
- Added checks for restricted class types before introspection
- Added security checks to
-
Enhanced Type Validation
- Improved validation in
JinjavaBeanELResolver.isRestrictedClass()to prevent instantiation of sensitive types - Added additional restricted types to the denylist
- Implemented deeper validation for types created via ObjectMapper deserialization
- Improved validation in
-
Configuration Protection
- Added checks to prevent creation of new
JinjavaConfigorJinjavaELContextinstances via ObjectMapper - Prevented modification of
readOnlyResolverconfiguration from untrusted templates - Implemented additional safeguards around ELResolver configuration
- Added checks to prevent creation of new
-
Collection Type Validation
- Implemented proper type validation in
HubLELResolverto prevent collection type wrapping bypasses - Added checks for wrapped types in collection deserialization
- Implemented validation for all types within collections against allowlists
- Implemented proper type validation in
-
ObjectMapper Restrictions
- Added additional restrictions on
ObjectMapper.enableDefaultTyping()to prevent enabling via less restrictive ELResolver - Ensured default typing cannot be enabled without proper authorization
- Added additional restrictions on
Information for Users: Upgrade to version 2.8.3 or 2.7.6 or later to address this vulnerability.
References
Project Resources
- Jinjava Source Code: github.com/HubSpot/jinjava
- Jinjava Releases: github.com/HubSpot/jinjava/releases
Security Standards & Classifications
- CWE-502: Deserialization of Untrusted Data
- CWE-913: Improper Control of Dynamically-Managed Code Resources
- CWE-94: Improper Control of Generation of Code ('Code Injection')
- CVSS v3.1: Common Vulnerability Scoring System
Additional Resources
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.hubspot.jinjava:jinjava | ≥ 2.8.0&&< 2.8.3 | 2.8.3com.hubspot.jinjava:jinjava:2.8.3 |
| ☕Maven | com.hubspot.jinjava:jinjava | all versions | 2.7.6com.hubspot.jinjava:jinjava:2.7.6 |
Detection & 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 2.8.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-25526 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-25526 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-25526. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-25526 in your dependencies?
O3 Security finds CVE-2026-25526 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.