# CVE-2026-123368: compose-lint: .env read through a symlink outside the project can expose the CI job's environment

Status: published. Published: 2026-11-09. Updated: 2026-11-13.

compose-lint is a Docker Compose security linter that identifies dangerous misconfigurations before deployment. From 0.22.0 until 0.31.0, compose-lint follows a sibling .env symbolic link outside the project without applying its normal containment check. From 0.28.0, the same gap also affects an include project_directory link outside the project. A pull request can reference a variable from the linked file, causing substitution to place runner file or process-environment data into finding messages written to logs, JSON, SARIF artifacts, and Code Scanning alerts. Reading /proc/self/environ can expose the remainder of the linter process environment because NUL-separated entries are treated as one value, although disclosure requires a workflow that processes untrusted changes with useful environment data and GitHub normally withholds secrets from fork pull requests. The pass or fail result is not changed. This issue is fixed in version 0.31.0.

## Remediation

- fix: compose-lint (pip): GitHub reports patched versions 0.31.0. Check the advisory for the affected release branch. (source: GitHub GHSA-6wcv-rj3c-mhv3) — https://github.com/tmatens/compose-lint/security/advisories/GHSA-6wcv-rj3c-mhv3
- fix: tmatens/compose-lint (actions): GitHub reports patched versions 0.31.0. Check the advisory for the affected release branch. (source: GitHub GHSA-6wcv-rj3c-mhv3) — https://github.com/tmatens/compose-lint/security/advisories/GHSA-6wcv-rj3c-mhv3
- fix: compose-lint (PyPI): OSV reports a fixed version 0.31.0. Check the advisory for supported release branches. (source: OSV GHSA-6wcv-rj3c-mhv3) — https://github.com/advisories/GHSA-6wcv-rj3c-mhv3
- fix: tmatens/compose-lint (GitHub Actions): OSV reports a fixed version 0.31.0. Check the advisory for supported release branches. (source: OSV GHSA-6wcv-rj3c-mhv3) — https://github.com/advisories/GHSA-6wcv-rj3c-mhv3
- fix: tmatens/compose-lint: OSV reports a fix at commit a6a7a76736de1c72abfa96c41ff8af556ffdc55f. (source: OSV GHSA-6wcv-rj3c-mhv3) — https://github.com/advisories/GHSA-6wcv-rj3c-mhv3

## Affected products and versions

- tmatens / compose-lint: >= 0.22.0, < 0.31.0 (affected). Source: CNA: GitHub_M
-  / compose-lint (compose-lint): >= 0.22.0, <= 0.30.0 (affected, GitHub advisory range). Source: GitHub GHSA-6wcv-rj3c-mhv3
-  / tmatens/compose-lint (tmatens/compose-lint): >= 0.22.0, <= 0.30.0 (affected, GitHub advisory range). Source: GitHub GHSA-6wcv-rj3c-mhv3
-  / compose-lint (compose-lint): 0.22.0 (affected, PyPI); 0.23.0 (affected, PyPI); 0.24.0 (affected, PyPI); 0.25.0 (affected, PyPI); 0.26.0 (affected, PyPI); 0.27.0 (affected, PyPI); 0.28.0 (affected, PyPI); 0.29.0 (affected, PyPI); 0.30.0 (affected, PyPI); Ecosystem version events: introduced 0.22.0; fixed 0.31.0. Source: OSV GHSA-6wcv-rj3c-mhv3
-  / tmatens/compose-lint (tmatens/compose-lint): v0.30.0 (affected, GitHub Actions); v0.29.0 (affected, GitHub Actions); v0.28.0 (affected, GitHub Actions); v0.27.0 (affected, GitHub Actions); v0.26.0 (affected, GitHub Actions); v0.25.0 (affected, GitHub Actions); v0.24.0 (affected, GitHub Actions); v0.23.0 (affected, GitHub Actions); v0.22.0 (affected, GitHub Actions); Ecosystem version events: introduced 0.22.0; fixed 0.31.0; Git commit history: introduced 811ef6b379dbc78d048fcedaf976205705d4a7c3; fixed a6a7a76736de1c72abfa96c41ff8af556ffdc55f. Source: OSV GHSA-6wcv-rj3c-mhv3

## Severity and prioritization

- CVSS 4.0: 2.3 (low); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N; source: CNA: GitHub_M

- CVSS 4.0: 2.3 (low); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: 0.48% as of 2026-11-12; percentile 41.71%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-22, CWE-59

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/tmatens/compose-lint/security/advisories/GHSA-6wcv-rj3c-mhv3 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/tmatens/compose-lint/pull/917 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/tmatens/compose-lint/commit/c43204ad4dab11d54e20574a52bc4e5835246ca5 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/tmatens/compose-lint/releases/tag/v0.31.0 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/tmatens/compose-lint/commit/c43204ad4dab11d54e20574a52bc4e5835246ca5 (security-advisories@github.com)

- https://github.com/tmatens/compose-lint/pull/917 (security-advisories@github.com)

- https://github.com/tmatens/compose-lint/releases/tag/v0.31.0 (security-advisories@github.com)

- https://github.com/tmatens/compose-lint/security/advisories/GHSA-6wcv-rj3c-mhv3 (security-advisories@github.com)

- https://github.com/tmatens/compose-lint/security/advisories/GHSA-6wcv-rj3c-mhv3 (GitHub Security Advisories; advisory)

- https://github.com/advisories/GHSA-6wcv-rj3c-mhv3 (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-6wcv-rj3c-mhv3 (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-123368; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123368; retrieved 2026-11-13; source updated 2026-11-12

- GitHub Security Advisories: https://github.com/tmatens/compose-lint/security/advisories/GHSA-6wcv-rj3c-mhv3; retrieved 2026-11-12; source updated 2026-11-10

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-6wcv-rj3c-mhv3; retrieved 2026-11-13; source updated 2026-11-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-123368; retrieved 2026-11-13; source updated Not reported

Revision: 5e96f938d34971a78418cdf800fffbfd656d21ef35efc2cc7dc9234edaff8706

Canonical: https://y2.dev/cve/CVE-2026-123368

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