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CVE-2026-41645

Nuclei: Environment variable disclosure via Response-Derived DSL Expressions

5.3 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

0.35%Up 0.3 points since May 8, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.3

Nuclei: Environment variable disclosure via Response-Derived DSL Expressions

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.

Record
CVE-2026-41645
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-94
Updated
2026-11-02
EUVDEUVD-2026-28498 5.3

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.

Record
EUVD-2026-28498
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-jm34-66cf-qpvr 5.3

Nuclei: Environment variable disclosure via Response-Derived DSL Expressions

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 the template variable map. A malicious target can return response data containing expressions like {{env_var_name}} which, when reused in a subsequent template request, resolve to actual environment variable values. This can expose sensitive host data like API keys, credentials, and tokens.

Without -ev enabled (the default), injected DSL expressions may still trigger helper functions such as {{md5("test")}}, but this has no meaningful security impact beyond unexpected behavior.

There is also a separate issue in hasLiteralsOnly(): it was evaluating helper expressions while deciding whether {{...}} contained unresolved variables, which caused validation logic to run side-effectful helpers even when the final request kept the value as a literal.

[!NOTE] The -env-vars / -ev option is off by default. Users who have not explicitly turned it on are not affected by the information disclosure aspect of this vulnerability.

Affected Users

  • CLI users running multi-step templates (with extractors or flow-based request chaining) that reuse response-derived values against untrusted or attacker-controlled targets, with the -ev flag enabled.
  • SDK users who have integrated Nuclei into platforms where EnvironmentVariables is set to true and scan targets are not fully trusted.

Patches

  • The vulnerability is fixed in Nuclei v3.8.0. Upgrading to this version is strongly recommended.
  • Relevant fix references: #7221, #7321.

Mitigation

Upgrade to Nuclei v3.8.0. The updated evaluation logic now collects expressions from the original template text before placeholder substitution and only evaluates those template-authored expressions.

If you have -ev enabled, disable it when scanning untrusted targets to avoid environment variable disclosure.

Workarounds

If upgrading is not an option right now, make sure -env-vars / -ev is not enabled when running multi-step templates against untrusted targets.

Acknowledgments

Nuclei thanks @gnuletik for reporting this issue through responsible disclosure via [email protected]

Record
GHSA-jm34-66cf-qpvr
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-94
Updated
2026-11-02
NVD 5.3

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.

Record
CVE-2026-41645
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-94
Updated
2026-11-02
OSVCVE-2026-41282 4.0

ProjectDiscovery Nuclei 3 before 3.8.0 allows DSL expression injection. This affects use of -env-vars for multi-step templates against untrusted targets (not the default configuration).

Record
CVE-2026-41282
CVSS 3.1
4.0 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N
Weakness
CWE-94
Updated
2026-11-02
OSV 5.3

Nuclei: Environment variable disclosure via Response-Derived DSL Expressions

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.

Record
CVE-2026-41645
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-94
Updated
2026-11-02
OSVGHSA-jm34-66cf-qpvr 5.3

Nuclei: Environment variable disclosure via Response-Derived DSL Expressions

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 the template variable map. A malicious target can return response data containing expressions like {{env_var_name}} which, when reused in a subsequent template request, resolve to actual environment variable values. This can expose sensitive host data like API keys, credentials, and tokens.

Without -ev enabled (the default), injected DSL expressions may still trigger helper functions such as {{md5("test")}}, but this has no meaningful security impact beyond unexpected behavior.

There is also a separate issue in hasLiteralsOnly(): it was evaluating helper expressions while deciding whether {{...}} contained unresolved variables, which caused validation logic to run side-effectful helpers even when the final request kept the value as a literal.

[!NOTE] The -env-vars / -ev option is off by default. Users who have not explicitly turned it on are not affected by the information disclosure aspect of this vulnerability.

Affected Users

  • CLI users running multi-step templates (with extractors or flow-based request chaining) that reuse response-derived values against untrusted or attacker-controlled targets, with the -ev flag enabled.
  • SDK users who have integrated Nuclei into platforms where EnvironmentVariables is set to true and scan targets are not fully trusted.

Patches

  • The vulnerability is fixed in Nuclei v3.8.0. Upgrading to this version is strongly recommended.
  • Relevant fix references: #7221, #7321.

Mitigation

Upgrade to Nuclei v3.8.0. The updated evaluation logic now collects expressions from the original template text before placeholder substitution and only evaluates those template-authored expressions.

If you have -ev enabled, disable it when scanning untrusted targets to avoid environment variable disclosure.

Workarounds

If upgrading is not an option right now, make sure -env-vars / -ev is not enabled when running multi-step templates against untrusted targets.

Acknowledgments

Nuclei thanks @gnuletik for reporting this issue through responsible disclosure via [email protected]

Record
GHSA-jm34-66cf-qpvr
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-94
Updated
2026-11-02
OSVGO-2026-5473 No score

Nuclei: Environment variable disclosure via Response-Derived DSL Expressions in github.com/projectdiscovery/nuclei

Nuclei: Environment variable disclosure via Response-Derived DSL Expressions in github.com/projectdiscovery/nuclei

Record
GO-2026-5473
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/projectdiscovery/nuclei/v3
Go
 3.0.0 up to 3.8.0
3.8.0
github.com/projectdiscovery/nuclei/v3
Go
From an advisory covering 2 CVEs
 3.0.0 up to 3.8.0
3.8.0
github.com/projectdiscovery/nuclei
Go
From an advisory covering 2 CVEs
 All versions None known
github.com/projectdiscovery/nuclei/v2
Go
From an advisory covering 2 CVEs
 All versions None known
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-41645 is a medium vulnerability (CVSS 5.3) in Projectdiscovery Nuclei, published April 20, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.35%, the 28th percentile. Fixed in github.com/projectdiscovery/nuclei/v3 3.8.0.

References

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