compose-lint: A .compose-lint.yml symlinked outside the project is read, and a parse error quotes part of the target

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.3 · 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 · score source

EPSS

• CVE-2026-123371: 0.45% estimated exploitation activity in the next 30 days; percentile 39.14 (FIRST EPSS, 2026-11-10). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact compose-lint automatically reads a `.compose-lint.yml` policy file beside the Compose file. It is meant to read nothing outside the project directory, but it follows that file if it is a symlink, wherever it points. A pull request can commit `.compose-lint.yml` as a symlink to a file on the CI runner. If the target is not valid YAML, the error compose-lint reports quotes part of the line the parser failed on. That quote reaches the job log (standard error), JSON `errors[]`, and the SARIF `toolExecutionNotifications`, which the Action uploads to Code Scanning. The run exits 2. What can be read is small. The quote is cut to about 30 characters around the error position, and the attacker cannot choose which line of the target the parser fails on. For an INI-style credentials file, this was the start of the second line (`aws_access_key_id = ` followed by the first characters of the value). Targets in `KEY=value` form, and YAML files that parse, disclosed no values in testing.…

Published by the source

10 Nov 2026, 15:57 UTC

Last modified by the source

10 Nov 2026, 16:15 UTC

Source last checked

11 Nov 2026, 07:05 UTC

1. Revision 2 · amended · 11 Nov 2026

   Amended from osv record GHSA-88f4-frh5-gmcr

2. Revision 1 · created · 10 Nov 2026

   Published from ghsa record GHSA-88f4-frh5-gmcr

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# Patch Next advisory brief: CVE-2026-123371

Advisory: compose-lint: A `.compose-lint.yml` symlinked outside the project is read, and a parse error quotes part of the target
IDs: CVE-2026-123371, GHSA-88f4-frh5-gmcr
Record: https://patchnext.com/advisories/cve-2026-123371 (revision 2, source checked 11 Nov 2026, 07:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: compose-lint 0.32.0; tmatens/compose-lint 0.32.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI compose-lint: affected >= 0.2.0, < 0.32.0; fixed in 0.32.0
- GitHub Actions tmatens/compose-lint: affected >= 0.2.0, < 0.32.0; fixed in 0.32.0

## Suggested inspection (read-only)
- `python -m pip show compose-lint`: prints the installed version. Run with the environment that serves production active.
- GitHub Actions tmatens/compose-lint: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on compose-lint, tmatens/compose-lint.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-88f4-frh5-gmcr (GitHub-reviewed advisory GHSA-88f4-frh5-gmcr lists affected ranges: PyPI compose-lint >=0.2.0 =0.2.0 <=0.31.0)
- Verified: https://osv.dev/vulnerability/GHSA-88f4-frh5-gmcr (OSV record GHSA-88f4-frh5-gmcr lists affected ranges: PyPI compose-lint >=0.2.0 =0.2.0 <0.32.0 (fixed))

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