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

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

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.

Products include 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.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

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: 1 proofs of concept on GitHub.

Other vulnerabilities in HubSpot jinjava

• CVE-2025-59340 jinjava Sandbox Bypass via JavaType-Based Deserialization Critical 9.8
• CVE-2020-12668 Unauthorized access to Class instance in Jinjava Medium 6.5
• CVE-2018-18893 Jinjava calls getClass Medium 5.3

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as CLEANSTART-2026-ST98100, GHSA-gjx9-j8f8-7j74, MINI-4m2v-j5r3-vrwv.