GHSA-WHR6-FGPQ-FPV9
Vulnerability from github – Published: 2026-11-10 15:57 – Updated: 2026-11-10 15:57Impact
Like Docker Compose, compose-lint follows symlinks when it reads a project's files. Unlike Compose, compose-lint up to 0.24.0 could then put the contents of a file from outside the project into its output, where the author of a pull request can read it.
A pull request can commit a symlink, under a name compose-lint reads, pointing at a file on the CI runner:
- The Compose file itself (0.2.0–0.24.0). A
compose.ymlthat is a symlink, whether the pre-commit hook passes its name or the Action or a bare run finds it. compose.override.yml(0.22.0–0.24.0), which compose-lint merges automatically.- A
COMPOSE_FILEentry (0.22.0–0.24.0) in a.envbeside the Compose file.
When the target is not valid YAML, the parse error quotes the line it failed on. Docker Compose, given the same file, reports only a line number. That line reaches standard error (the job log), JSON errors[], and the SARIF toolExecutionNotifications, which the Action uploads to Code Scanning.
A fourth route: from 0.23.0, a symlinked env_file: target makes CL-0020 and CL-0021 report the credential-like key names in a file outside the project. Values are not printed.
What can be read is one line of a file chosen by path, at the point where the YAML parser fails, which the attacker cannot choose; or key names. A symlink to /proc/self/environ gave neither in testing. The pass/fail result is not affected. On a public repository the job log is visible to the pull request's author.
Found during an internal pre-1.0 security review.
GitHub Action. Action tags v0.18.0 through v0.24.0 install their own compose-lint version and are affected. Earlier tags install the newest release unless version: is set; they were affected while that was 0.24.0 or earlier.
Docker image. composelint/compose-lint tags 0.3.3 through 0.24.0, and the matching minor tags, are affected. Inside the container a symlink resolves within the container, so what can be read is the container's own files and anything mounted into it. Fixed from 0.25.0.
Patches
Fixed in 0.25.0. Parse errors no longer quote the source line; the error and its line and column are kept. env_file: targets and COMPOSE_FILE entries that resolve outside the project are also refused, with the existing outside-the-project note. Symlinks that stay inside the project still work.
From 0.25.0 through 0.31.0, a committed symlink to a target that is itself a Compose file could still be read, and its values could reach findings. 0.32.0 stops following a discovered, named or override Compose file whose link leaves the checkout.
A related gap for the sibling .env file is covered by GHSA-6wcv-rj3c-mhv3, and one for a symlinked .compose-lint.yml by GHSA-88f4-frh5-gmcr.
Workarounds
- Upgrade to 0.25.0 or later.
- On older versions, don't run compose-lint on untrusted pull requests on a machine whose files outside the checkout hold credentials.
--no-envcloses theCOMPOSE_FILEandenv_file:routes, but not the others.
Reproduction
project/compose.yml -> /path/outside/project/credentials (symlink)
compose-lint --format sarif compose.yml on 0.24.0 exits 2, and the SARIF notification quotes a line of the linked file. On 0.25.0 the error gives only the line and column.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.24.0"
},
"package": {
"ecosystem": "PyPI",
"name": "compose-lint"
},
"ranges": [
{
"events": [
{
"introduced": "0.2.0"
},
{
"fixed": "0.25.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.24.0"
},
"package": {
"ecosystem": "GitHub Actions",
"name": "tmatens/compose-lint"
},
"ranges": [
{
"events": [
{
"introduced": "0.2.0"
},
{
"fixed": "0.25.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-123373"
],
"database_specific": {
"cwe_ids": [
"CWE-209",
"CWE-59"
],
"github_reviewed": true,
"github_reviewed_at": "2026-11-10T15:57:10Z",
"nvd_published_at": "2026-11-09T18:17:26Z",
"severity": "LOW"
},
"details": "### Impact\n\nLike Docker Compose, compose-lint follows symlinks when it reads a project\u0027s files. Unlike Compose, compose-lint up to 0.24.0 could then put the contents of a file from *outside* the project into its output, where the author of a pull request can read it.\n\nA pull request can commit a symlink, under a name compose-lint reads, pointing at a file on the CI runner:\n\n- **The Compose file itself (0.2.0\u20130.24.0).** A `compose.yml` that is a symlink, whether the pre-commit hook passes its name or the Action or a bare run finds it.\n- **`compose.override.yml` (0.22.0\u20130.24.0),** which compose-lint merges automatically.\n- **A `COMPOSE_FILE` entry (0.22.0\u20130.24.0)** in a `.env` beside the Compose file.\n\nWhen the target is not valid YAML, the parse error quotes the line it failed on. Docker Compose, given the same file, reports only a line number. That line reaches standard error (the job log), JSON `errors[]`, and the SARIF `toolExecutionNotifications`, which the Action uploads to Code Scanning.\n\nA fourth route: from 0.23.0, a symlinked `env_file:` target makes CL-0020 and CL-0021 report the credential-like **key names** in a file outside the project. Values are not printed.\n\nWhat can be read is one line of a file chosen by path, at the point where the YAML parser fails, which the attacker cannot choose; or key names. A symlink to `/proc/self/environ` gave neither in testing. The pass/fail result is not affected. On a public repository the job log is visible to the pull request\u0027s author.\n\nFound during an internal pre-1.0 security review.\n\n**GitHub Action.** Action tags v0.18.0 through v0.24.0 install their own compose-lint version and are affected. Earlier tags install the newest release unless `version:` is set; they were affected while that was 0.24.0 or earlier.\n\n**Docker image.** `composelint/compose-lint` tags 0.3.3 through 0.24.0, and the matching minor tags, are affected. Inside the container a symlink resolves within the container, so what can be read is the container\u0027s own files and anything mounted into it. Fixed from `0.25.0`.\n\n### Patches\n\nFixed in 0.25.0. Parse errors no longer quote the source line; the error and its line and column are kept. `env_file:` targets and `COMPOSE_FILE` entries that resolve outside the project are also refused, with the existing outside-the-project note. Symlinks that stay inside the project still work.\n\nFrom 0.25.0 through 0.31.0, a committed symlink to a target that is itself a Compose file could still be read, and its values could reach findings. 0.32.0 stops following a discovered, named or override Compose file whose link leaves the checkout.\n\nA related gap for the sibling `.env` file is covered by GHSA-6wcv-rj3c-mhv3, and one for a symlinked `.compose-lint.yml` by GHSA-88f4-frh5-gmcr.\n\n### Workarounds\n\n- Upgrade to 0.25.0 or later.\n- On older versions, don\u0027t run compose-lint on untrusted pull requests on a machine whose files outside the checkout hold credentials. `--no-env` closes the `COMPOSE_FILE` and `env_file:` routes, but not the others.\n\n### Reproduction\n\n```\nproject/compose.yml -\u003e /path/outside/project/credentials (symlink)\n```\n\n`compose-lint --format sarif compose.yml` on 0.24.0 exits 2, and the SARIF notification quotes a line of the linked file. On 0.25.0 the error gives only the line and column.",
"id": "GHSA-whr6-fgpq-fpv9",
"modified": "2026-11-10T15:57:10Z",
"published": "2026-11-10T15:57:10Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/tmatens/compose-lint/security/advisories/GHSA-whr6-fgpq-fpv9"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123373"
},
{
"type": "WEB",
"url": "https://github.com/tmatens/compose-lint/pull/721"
},
{
"type": "WEB",
"url": "https://github.com/tmatens/compose-lint/commit/364814329417dbbc34d1ad2f3981f8a7a023799e"
},
{
"type": "PACKAGE",
"url": "https://github.com/tmatens/compose-lint"
},
{
"type": "WEB",
"url": "https://github.com/tmatens/compose-lint/releases/tag/v0.25.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "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",
"type": "CVSS_V4"
}
],
"summary": "compose-lint: A committed symlink makes compose-lint quote a file from outside the project into its output"
}
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.
Loading timeline…
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.