A vulnerability in the Goja JavaScript engine used by Nuclei's `javascript:` protocol allows arbitrary native code execution on the scanner host when running untrusted JavaScript templates.
**Affected Component**
The issue is in the Goja JavaScript runtime embedded in Nuclei's JavaScript protocol (`pkg/js/`). An out-of-bounds heap write in the engine can be exploited to achieve native code execution during template evaluation.
**Description**
Nuclei uses the Goja engine to execute `javascript:` protocol templates. A memory safety vulnerability in Goja allows attacker-controlled JavaScript to corrupt heap memory and execute arbitrary native code on the host running Nuclei.
Because `javascript:` templates execute without the `-code` flag and unsigned JavaScript templates run by default, a malicious template from an untrusted source can trigger code execution during a normal scan. The vulnerability could also be reached through a template's `init` section, which runs during template initialization before other security checks complete.
> [!NOTE]
JavaScript templates do not require the `-code` flag and are not subject to the code-template signing requirement on affected versions. Nuclei v3.11.0 adds a separate signing requirement for JavaScript templates as additional defense in depth.
**Affected Users**
- **CLI users** running untrusted or third-party `javascript:` templates.
- **SDK users** who integrate Nuclei into platforms where end users can supply JavaScript templates.
**Patches**
- The vulnerability is fixed in Nuclei v3.10.0 by updating the Goja dependency. Upgrading is strongly recommended.
- Fix reference: https://github.com/projectdiscovery/nuclei/pull/7467
- Additional hardening in v3.11.0 requires cryptographic signatures for JavaScript templates: https://github.com/projectdiscovery/nuclei/pull/7514
**Mitigation**
Upgrade to Nuclei v3.10.0 or later. For additional protection, upgrade to v3.11.0 where JavaScript templates also require valid signatures.
In the meantime, avoid running JavaScript templates from unverified sources.
**Workarounds**
If upgrading is not an option, do not run untrusted JavaScript templates. There is no configuration flag that mitigates native code execution on affected versions.
**Acknowledgments**
Thanks to Dylan Pindur ([@dpindur](https://github.com/dpindur)) and Adam Kues ([@akues-an](https://github.com/akues-an)) of the Assetnote security research team for reporting this issue through responsible disclosure via
[email protected].
