Bug 2538484 (CVE-2026-76805)

Summary: CVE-2026-76805 github.com/projectdiscovery/nuclei: Nuclei: Environment Variable Disclosure in DAST/Fuzz Mode
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Nuclei, a vulnerability scanner. A malicious scan target can exploit a vulnerability in the Dynamic Application Security Testing (DAST)/fuzz mode where response content is evaluated twice and reinterpreted as template syntax. This allows the scan target to disclose sensitive scanner-host environment variables, such as credentials, API keys, or tokens. This issue occurs when the -env-vars option is enabled, a multi-step DAST or fuzz template is used, and response data is reused through an internal extractor.
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Description OSIDB Bzimport 2026-09-22 18:40:28 UTC 
Nuclei is a vulnerability scanner built on a simple YAML-based DSL. From 3.0.0 until 3.10.0, the DAST/fuzz payload path in pkg/fuzz/parts.go can evaluate substituted runtime data more than once, creating a second evaluation pass that allows response content captured by an internal: true extractor in one protocol step to be reinterpreted as template syntax in a later fuzz step. This vulnerability is an incomplete fix for CVE-2026-41645: the prior remediation made expressions.Evaluate() single-pass within one call but did not prevent DAST/fuzz callers from evaluating substituted output again. When -env-vars is enabled, a malicious scan target can return marker-shaped content that resolves against the template variable map and discloses scanner-host environment variables such as credentials, API keys, or tokens. The vulnerability requires a multi-step DAST or fuzz template, response data reused through an internal extractor, and explicit environment-variable expansion; users who do not enable -env-vars are not affected by the sensitive-information disclosure. This issue is fixed in version 3.10.0.