GHSA-6F4G-XM8V-PGV6

Vulnerability from github – Published: 2026-11-10 15:56 – Updated: 2026-11-10 15:56
VLAI
Summary
compose-lint: Compose file text can issue GitHub Actions workflow commands through the compose-lint Action
Details

Impact

The GitHub Actions runner treats certain text in a step's output as commands. The legacy form, ##[command], is recognized anywhere in a line. compose-lint's text report prints service names, environment keys and lines of the Compose file, and it does not neutralize ##[. Inside the compose-lint Action, a Compose file from a pull request can therefore:

  • create fake error or warning annotations on the pull request (##[error], ##[warning])
  • fold the rest of the log, including the real verdict, out of sight (##[group])
  • blank out chosen strings for the rest of the log (##[add-mask])

GitHub has postponed removing the deprecated set-output log command, so the runner still honors it. A test run of the Action on a GitHub-hosted runner confirmed that a ::set-output line from a Compose file is processed. Whether it can override the Action's own sarif-written output, which decides whether the SARIF upload step runs, has not been tested.

The exit code and the pass/fail result are not affected. Azure Pipelines parses the same ##[ syntax, so the pip package is listed for anyone printing the text report in other CI systems.

Found during an internal pre-1.0 security review.

Patches

Fixed in 0.31.0. The Action stops the runner from processing workflow commands while compose-lint's output is printed, using a random stop-commands token. The text report also escapes ##[, and :: at the start of a line, in anything taken from the Compose file.

Workarounds

  • In your own workflow, wrap the compose-lint step in ::stop-commands::<random token> and ::<random token>::.
  • Use --format json or --format sarif rather than the text report when linting untrusted pull requests.

Reproduction

services:
  web:
    image: "nginx:1.25"
    environment:
      "##[error]DB_PASSWORD": placeholder
  "##[group]svc":
    image: "nginx:1.25"
    privileged: true

Run through the Action, this produces a fake error annotation and folds the remaining log lines, including the FAIL verdict, into a collapsed group.

Severity
4.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
5.3 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.30.0"
      },
      "package": {
        "ecosystem": "GitHub Actions",
        "name": "tmatens/compose-lint"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.2.0"
            },
            {
              "fixed": "0.31.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.30.0"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "compose-lint"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.31.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-123369"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-117",
      "CWE-150"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-11-10T15:56:59Z",
    "nvd_published_at": "2026-11-09T18:17:25Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nThe GitHub Actions runner treats certain text in a step\u0027s output as commands. The legacy form, `##[command]`, is recognized anywhere in a line. compose-lint\u0027s text report prints service names, environment keys and lines of the Compose file, and it does not neutralize `##[`. Inside the compose-lint Action, a Compose file from a pull request can therefore:\n\n- create fake error or warning annotations on the pull request (`##[error]`, `##[warning]`)\n- fold the rest of the log, including the real verdict, out of sight (`##[group]`)\n- blank out chosen strings for the rest of the log (`##[add-mask]`)\n\nGitHub has postponed removing the deprecated `set-output` log command, so the runner still honors it. A test run of the Action on a GitHub-hosted runner confirmed that a `::set-output` line from a Compose file is processed. Whether it can override the Action\u0027s own `sarif-written` output, which decides whether the SARIF upload step runs, has not been tested.\n\nThe exit code and the pass/fail result are not affected. Azure Pipelines parses the same `##[` syntax, so the pip package is listed for anyone printing the text report in other CI systems.\n\nFound during an internal pre-1.0 security review.\n\n### Patches\n\nFixed in 0.31.0. The Action stops the runner from processing workflow commands while compose-lint\u0027s output is printed, using a random `stop-commands` token. The text report also escapes `##[`, and `::` at the start of a line, in anything taken from the Compose file.\n\n### Workarounds\n\n- In your own workflow, wrap the compose-lint step in `::stop-commands::\u003crandom token\u003e` and `::\u003crandom token\u003e::`.\n- Use `--format json` or `--format sarif` rather than the text report when linting untrusted pull requests.\n\n### Reproduction\n\n```yaml\nservices:\n  web:\n    image: \"nginx:1.25\"\n    environment:\n      \"##[error]DB_PASSWORD\": placeholder\n  \"##[group]svc\":\n    image: \"nginx:1.25\"\n    privileged: true\n```\n\nRun through the Action, this produces a fake error annotation and folds the remaining log lines, including the FAIL verdict, into a collapsed group.",
  "id": "GHSA-6f4g-xm8v-pgv6",
  "modified": "2026-11-10T15:56:59Z",
  "published": "2026-11-10T15:56:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/tmatens/compose-lint/security/advisories/GHSA-6f4g-xm8v-pgv6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123369"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tmatens/compose-lint/pull/918"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tmatens/compose-lint/commit/672bd11145621f787c295fb11f3a859cdec1b38d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/tmatens/compose-lint"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tmatens/compose-lint/releases/tag/v0.31.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:L/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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "compose-lint: Compose file text can issue GitHub Actions workflow commands through the compose-lint Action"
}



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