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

published 2026-11-09 6h ago modified 2026-11-09 5h ago also EUVD-2026-120123

cvss: 2.3; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: —; no EPSS score yet
public exploits: 0; none known

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.

Patch / fix

links 3

github.com/tmatens/compose-lint@c43204a commit
github.com/tmatens/compose-lint#917 pull request
github.com/tmatens/compose-lint/releases/tag/v0.31.0 release

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CVSS scores

assigned by	version	score	vector
CNA	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
CNA	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/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

Affected products

tmatens compose-lint

Classification

Weakness

CWE-22 Improper Limitation of a Pathname to a Restricted Directory
CWE-59 Improper Link Resolution Before File Access

References

Sources

CVE List CVE-2026-123368
NVD CVE-2026-123368

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.