Summary
Nuclei: Arbitrary Code Execution via Goja JavaScript Engine Vulnerability
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) and Adam Kues (@akues-an) of the Assetnote security research team for reporting this issue through responsible disclosure via [email protected].
Impact
Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.
CVE-2026-76819 has a CVSS score of 8.6 (High). The vector is requires local access, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.10.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-76819? CVE-2026-76819 is a high-severity code injection vulnerability in github.com/projectdiscovery/nuclei/v3 (go), affecting versions >= 3.0.0, < 3.10.0. It is fixed in 3.10.0. Untrusted input is evaluated as executable code within the application's runtime environment.
- How severe is CVE-2026-76819? CVE-2026-76819 has a CVSS score of 8.6 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/projectdiscovery/nuclei/v3 are affected by CVE-2026-76819? github.com/projectdiscovery/nuclei/v3 (go) versions >= 3.0.0, < 3.10.0 is affected.
- Is there a fix for CVE-2026-76819? Yes. CVE-2026-76819 is fixed in 3.10.0. Upgrade to this version or later.
- Is CVE-2026-76819 exploitable, and should I be worried? Whether CVE-2026-76819 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-76819 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-76819? Upgrade
github.com/projectdiscovery/nuclei/v3to 3.10.0 or later.