# CVE-2026-25526: JinJava Bypass through ForTag leads to Arbitrary Java Execution

> Attackers can execute arbitrary Java code and access files by bypassing sandbox restrictions in the JinJava template engine.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Feb 2026
- **Updated:** 5 Feb 2026
- **Also known as:** CLEANSTART-2026-ST98100, GHSA-gjx9-j8f8-7j74, MINI-4m2v-j5r3-vrwv

## What is CVE-2026-25526?

CVE-2026-25526 is a critical code injection vulnerability in HubSpot jinjava, published on 4 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-1336 (Improper Neutralization of Special Elements Used in a Template Engine)

## Which versions are affected by CVE-2026-25526?

4 open source packages ship an affected version, including com.hubspot.jinjava:jinjava. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `com.hubspot.jinjava:jinjava` | Maven | All versions | 2.7.6 |
| `com.hubspot.jinjava:jinjava` | Maven | All versions | 2.7.6 |
| `com.hubspot.jinjava:jinjava` | Maven | From 2.8.0 | 2.8.3 |
| `com.hubspot.jinjava:jinjava` | Maven | From 2.8.0 | 2.8.3 |

Products: Hubspot Jinjava.

## How do I fix CVE-2026-25526?

Upgrade com.hubspot.jinjava:jinjava to a fixed version for your release line: 2.7.6 or 2.8.3.

## Is CVE-2026-25526 being exploited?

There is no known exploitation of CVE-2026-25526 in the wild and no public exploit code.

Public exploit code:

- lab setup + exploits for CVE-2026-25526 (github_poc): https://github.com/av4nth1ka/jinjava-cve-2026-25526-poc

## Other vulnerabilities in HubSpot jinjava

- [CVE-2025-59340](https://insights.sbomify.com/CVE-2025-59340/): jinjava Sandbox Bypass via JavaType-Based Deserialization (critical 9.8)
- [CVE-2020-12668](https://insights.sbomify.com/CVE-2020-12668/): Unauthorized access to Class instance in Jinjava (medium 6.5)
- [CVE-2018-18893](https://insights.sbomify.com/CVE-2018-18893/): Jinjava calls getClass (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-25526 and fix it if it is affected.

What it is: CVE-2026-25526 is a critical code injection vulnerability in HubSpot jinjava, published on 4 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-25526 in the wild and no public exploit code.

Affected packages and fixed versions:
- com.hubspot.jinjava:jinjava (Maven): affected all versions; fixed in 2.7.6
- com.hubspot.jinjava:jinjava (Maven): affected all versions; fixed in 2.7.6
- com.hubspot.jinjava:jinjava (Maven): affected from 2.8.0; fixed in 2.8.3
- com.hubspot.jinjava:jinjava (Maven): affected from 2.8.0; fixed in 2.8.3

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-25526/ (Markdown: https://insights.sbomify.com/CVE-2026-25526/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-25526
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-25526
- OSV: https://osv.dev/vulnerability/CVE-2026-25526

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-25526/
Summaries are generated and may contain mistakes; the official description above is the record.