{"id":"CVE-2026-76805","aliases":["EUVD-2026-84557","GHSA-jpvm-9frm-hjcq","GO-2026-6571"],"status":"published","title":"Nuclei: Environment Variable Disclosure via Response-Derived Data in DAST/Fuzz Mode","description":"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.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.0041,"percentile":0.35628,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-200"],"published":"2026-09-22T16:48:49Z","modified":"2026-10-28T02:30:50Z","fixes":[{"ecosystem":"Go","package":"github.com/projectdiscovery/nuclei/v3","fixed_in":["3.10.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Go","package":"github.com/projectdiscovery/nuclei/v3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0"},{"fixed":"3.10.0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/projectdiscovery/nuclei/v3","ranges":[{"type":"SEMVER","events":[{"introduced":"3.0.0"},{"fixed":"3.10.0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/projectdiscovery/nuclei","ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/projectdiscovery/nuclei/v2","ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/projectdiscovery/nuclei/v3","ranges":[{"type":"SEMVER","events":[{"introduced":"3.0.0"},{"fixed":"3.10.0"}]}]}],"products":[{"vendor":"projectdiscovery","product":"nuclei"}],"references":[{"url":"https://github.com/projectdiscovery/nuclei/security/advisories/GHSA-jpvm-9frm-hjcq","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/projectdiscovery/nuclei/pull/7499","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/projectdiscovery/nuclei/commit/ccbfb12bd01447ba25f6e755dfb2bee677736da6","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/projectdiscovery/nuclei/releases/tag/v3.10.0","tags":["x_refsource_MISC","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-76805","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-jpvm-9frm-hjcq"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/76xxx/CVE-2026-76805.json","tags":["advisory"]},{"url":"https://github.com/projectdiscovery/nuclei","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-76805","title":"Nuclei: Environment Variable Disclosure via Response-Derived Data in DAST/Fuzz Mode","description":"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.","status":"published","published":"2026-09-22T16:48:49.791Z","modified":"2026-09-22T18:19:16.72Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T13:46:10.323375Z"}],"euvd":[{"id":"EUVD-2026-84557","description":"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.","status":"published","published":"2026-09-22T16:48:49Z","modified":"2026-09-22T18:19:16Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T17:28:02.149692Z"}],"ghsa":[{"id":"GHSA-jpvm-9frm-hjcq","title":"Nuclei: Environment Variable Disclosure via Response-Derived Data in DAST/Fuzz Mode","description":"A vulnerability in Nuclei's DAST/fuzz expression evaluation path allows a malicious target server to trigger disclosure of scanner-host environment variables when the `-env-vars` / `-ev` option is explicitly enabled.\n\nThis is an incomplete fix for [CVE-2026-41645](https://github.com/projectdiscovery/nuclei/security/advisories/GHSA-jm34-66cf-qpvr) / GHSA-jm34-66cf-qpvr. The original fix hardened `expressions.Evaluate()` to be single-pass within one call, but did not address callers that invoked evaluation multiple times on substituted output in the DAST/fuzz pipeline.\n\n**Affected Component**\n\nThe issue is in the DAST/fuzz payload evaluation path (`pkg/fuzz/parts.go`) and the shared template rendering boundary. When a multi-step template captures response data via an internal extractor and reuses it in a subsequent fuzz step, the fuzz evaluator could treat the substituted response content as fresh template syntax on a second evaluation pass.\n\n**Description**\n\nIn DAST/fuzz mode, payload evaluation previously ran expression substitution more than once on the same value. Response-derived content captured by an `internal: true` extractor in a prior protocol step could flow into a fuzz payload and be reinterpreted as DSL/helper syntax on a subsequent pass.\n\nWhen `-env-vars` (`-ev`) is enabled, environment variables are merged into the template variable map. A malicious target can return response data containing expressions like `{{env_var_name}}` which, when reused in a subsequent fuzz step, resolve to actual environment variable values. This can expose sensitive host data such as API keys, credentials, and tokens.\n\nWithout `-ev` enabled (the default), response-derived data may still cause other DSL helpers to run, but that behavior is not treated as a security issue and has no meaningful security impact beyond unexpected behavior.\n\n\u003e [!NOTE]\nThe `-env-vars` / `-ev` option is off by default. Users who have not explicitly enabled it are not affected by this vulnerability.\n\n**Affected Users**\n\n- **CLI users** running `nuclei -dast` (or fuzzing) with multi-step templates that chain an internal extractor into a subsequent fuzz step against untrusted targets, with the `-ev` flag enabled.\n- **SDK users** who integrate Nuclei with the fuzz pipeline enabled, `EnvironmentVariables` set to `true`, and scan targets that are not fully trusted.\n\n**Patches**\n\n- The vulnerability is fixed in Nuclei v3.10.0. Upgrading is strongly recommended.\n- Fix reference: https://github.com/projectdiscovery/nuclei/pull/7499\n- Related original fix: https://github.com/projectdiscovery/nuclei/pull/7221, https://github.com/projectdiscovery/nuclei/pull/7321\n\n**Mitigation**\n\nUpgrade to Nuclei v3.10.0, where template-authored text is rendered once through a shared rendering boundary and runtime values from responses, extractors, and constants remain opaque data.\n\nIf you have `-ev` enabled, disable it when scanning untrusted targets to avoid environment variable disclosure.\n\n**Workarounds**\n\nIf upgrading is not an option, ensure `-env-vars` / `-ev` is not enabled when running DAST/fuzz scans with multi-step templates against untrusted targets.\n\n**Acknowledgments**\n\nThanks to @BerSecHub for reporting this issue.","status":"published","published":"2026-09-22T20:37:24Z","modified":"2026-09-22T20:37:27Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T14:41:20.575159Z"}],"nvd":[{"id":"CVE-2026-76805","description":"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.","status":"published","published":"2026-09-22T17:17:25.087Z","modified":"2026-09-23T18:28:25.093Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T14:12:50.368368Z"}],"osv":[{"id":"CVE-2026-76805","title":"Nuclei: Environment Variable Disclosure via Response-Derived Data in DAST/Fuzz Mode","description":"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.","status":"published","published":"2026-09-22T16:48:49.791Z","modified":"2026-10-28T02:30:50.218675223Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T15:45:17.102988Z"},{"id":"GHSA-jpvm-9frm-hjcq","title":"Nuclei: Environment Variable Disclosure via Response-Derived Data in DAST/Fuzz Mode","description":"A vulnerability in Nuclei's DAST/fuzz expression evaluation path allows a malicious target server to trigger disclosure of scanner-host environment variables when the `-env-vars` / `-ev` option is explicitly enabled.\n\nThis is an incomplete fix for [CVE-2026-41645](https://github.com/projectdiscovery/nuclei/security/advisories/GHSA-jm34-66cf-qpvr) / GHSA-jm34-66cf-qpvr. The original fix hardened `expressions.Evaluate()` to be single-pass within one call, but did not address callers that invoked evaluation multiple times on substituted output in the DAST/fuzz pipeline.\n\n**Affected Component**\n\nThe issue is in the DAST/fuzz payload evaluation path (`pkg/fuzz/parts.go`) and the shared template rendering boundary. When a multi-step template captures response data via an internal extractor and reuses it in a subsequent fuzz step, the fuzz evaluator could treat the substituted response content as fresh template syntax on a second evaluation pass.\n\n**Description**\n\nIn DAST/fuzz mode, payload evaluation previously ran expression substitution more than once on the same value. Response-derived content captured by an `internal: true` extractor in a prior protocol step could flow into a fuzz payload and be reinterpreted as DSL/helper syntax on a subsequent pass.\n\nWhen `-env-vars` (`-ev`) is enabled, environment variables are merged into the template variable map. A malicious target can return response data containing expressions like `{{env_var_name}}` which, when reused in a subsequent fuzz step, resolve to actual environment variable values. This can expose sensitive host data such as API keys, credentials, and tokens.\n\nWithout `-ev` enabled (the default), response-derived data may still cause other DSL helpers to run, but that behavior is not treated as a security issue and has no meaningful security impact beyond unexpected behavior.\n\n\u003e [!NOTE]\nThe `-env-vars` / `-ev` option is off by default. Users who have not explicitly enabled it are not affected by this vulnerability.\n\n**Affected Users**\n\n- **CLI users** running `nuclei -dast` (or fuzzing) with multi-step templates that chain an internal extractor into a subsequent fuzz step against untrusted targets, with the `-ev` flag enabled.\n- **SDK users** who integrate Nuclei with the fuzz pipeline enabled, `EnvironmentVariables` set to `true`, and scan targets that are not fully trusted.\n\n**Patches**\n\n- The vulnerability is fixed in Nuclei v3.10.0. Upgrading is strongly recommended.\n- Fix reference: https://github.com/projectdiscovery/nuclei/pull/7499\n- Related original fix: https://github.com/projectdiscovery/nuclei/pull/7221, https://github.com/projectdiscovery/nuclei/pull/7321\n\n**Mitigation**\n\nUpgrade to Nuclei v3.10.0, where template-authored text is rendered once through a shared rendering boundary and runtime values from responses, extractors, and constants remain opaque data.\n\nIf you have `-ev` enabled, disable it when scanning untrusted targets to avoid environment variable disclosure.\n\n**Workarounds**\n\nIf upgrading is not an option, ensure `-env-vars` / `-ev` is not enabled when running DAST/fuzz scans with multi-step templates against untrusted targets.\n\n**Acknowledgments**\n\nThanks to @BerSecHub for reporting this issue.","status":"published","published":"2026-09-22T20:37:24Z","modified":"2026-10-01T20:55:51.679978244Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T15:46:50.687609Z"},{"id":"GO-2026-6571","title":"Nuclei: Environment Variable Disclosure via Response-Derived Data in DAST/Fuzz Mode in github.com/projectdiscovery/nuclei","description":"Nuclei: Environment Variable Disclosure via Response-Derived Data in DAST/Fuzz Mode in github.com/projectdiscovery/nuclei","status":"published","published":"2026-10-01T20:23:38Z","modified":"2026-10-01T20:45:14.100051683Z","updated_at":"2026-11-02T15:47:03.11707Z"}]}}