Nuclei: Environment variable disclosure via Response-Derived DSL Expressions

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-41645: 0.35% estimated exploitation activity in the next 30 days; percentile 28.81 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

A vulnerability in Nuclei's expression evaluation engine makes it possible for a malicious target server to inject and execute supported DSL expressions. This happens when HTTP response data containing helper/function syntax gets reused by multi-step templates. If the -env-vars / -ev option is explicitly enabled, this can expose host environment variables. That option is off by default, so standard configurations are not affected by the information disclosure risk. Affected Component The issue lives in expressions.Evaluate() at pkg/protocols/common/expressions/ and in the unresolved-variable validation path (hasLiteralsOnly()). Description expressions.Evaluate() replaces placeholders first, then scans the substituted output for expressions. Because of this two-pass approach, response-derived values (including extractor output and response body content) can be reinterpreted as DSL/helper syntax on the second pass. When -env-vars (-ev) is enabled, environment variables get merged into…

Published by the source

22 Apr 2026, 19:59 UTC

Last modified by the source

11 May 2026, 13:30 UTC

Source last checked

26 Oct 2026, 15:20 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-jm34-66cf-qpvr

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# Patch Next advisory brief: CVE-2026-41645

Advisory: Nuclei: Environment variable disclosure via Response-Derived DSL Expressions
IDs: CVE-2026-41645, GHSA-jm34-66cf-qpvr
Record: https://patchnext.com/advisories/cve-2026-41645 (revision 1, source checked 26 Oct 2026, 15:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/projectdiscovery/nuclei/v3 3.8.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/projectdiscovery/nuclei/v3: affected >= 3.0.0, < 3.8.0; fixed in 3.8.0

## Suggested inspection (read-only)
- Go github.com/projectdiscovery/nuclei/v3: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/projectdiscovery/nuclei/v3.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-jm34-66cf-qpvr (GitHub-reviewed advisory GHSA-jm34-66cf-qpvr lists affected ranges: Go github.com/projectdiscovery/nuclei/v3 >=3.0.0 <3.8.0)

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