CVE-2026-41645
MEDIUMCVE-2026-41645 is a medium-severity (CVSS 5.3) vulnerability in github.com/projectdiscovery/nuclei/v3. O3 Security confirms whether CVE-2026-41645 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Nuclei: Environment variable disclosure via Response-Derived DSL Expressions
Blast Radius
github.com/projectdiscovery/nuclei/v3Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Nuclei is a vulnerability scanner built on a simple YAML-based DSL. From version 3.0.0 to before version 3.8.0, 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. This issue has been patched in version 3.8.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/projectdiscovery/nuclei/v3 | ≥ 3.0.0&&< 3.8.0 | 3.8.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/projectdiscovery/nuclei/v3. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/projectdiscovery/nuclei/v3 to 3.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41645 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-41645 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-41645. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-41645 in your dependencies?
O3 detects CVE-2026-41645 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.