{"id":"CVE-2026-59871","aliases":["GHSA-w8wr-v893-vjvp"],"url":"https://o3.security/vulnerability/CVE-2026-59871","summary":"node-tar: Process crash via PAX numeric path type confusion","details":"### Summary\n\nA crafted 2.5KB tar archive crashes any Node.js process that extracts it. The PAX header parser coerces all-digit path values to JavaScript numbers, which causes an uncaught TypeError when downstream code calls `.split('/')` on the numeric value. Error handlers and `strict: false` cannot intercept the crash.\n\n### Details\n\nIn `pax.ts` line 180, `parseKV` converts PAX values matching `/^[0-9]+$/` to numbers via `+v`. This applies to all fields including `path` and `linkpath`. When a PAX header sets `path` to an all-digit string like `\"12345\"`, the value becomes the number `12345`.\n\nThis number flows through Header -> ReadEntry -> Unpack.CHECKPATH, where `normalizeWindowsPath(entry.path).split('/')` throws a TypeError because numbers don't have `.split()`.\n\nThe throw is synchronous during event emission and bypasses all error handling:\n- `strict: false` does not help\n- `'error'` event handlers do not catch it\n- `'warn'` handlers do not catch it\n- The TypeError propagates through the event emitter stack as an uncaughtException\n\nDirectory, SymbolicLink, and Link type entries reach CHECKPATH and crash. File type entries crash earlier in Header constructor at `this.path.slice(-1)`, but that throw is caught and emitted as a warning only.\n\n### PoC\n\nCreate a tar archive with a PAX extended header containing an all-digit path:\n\n```\nPAX header body: \"18 path=12345\\n\"\nEntry type: Directory (type '5')\n```\n\nExtract it:\n```js\nconst tar = require('tar');\n\n// All of these crash with TypeError: t.split is not a function\ntar.extract({ file: 'malicious.tar', cwd: '/tmp/test' });\n\n// Error handlers don't help:\ntar.extract({ file: 'malicious.tar', cwd: '/tmp/test', strict: false })\n  .on('error', (err) => { /* never reached */ })\n  .on('warn', (code, msg) => { /* never reached */ });\n```\n\nThe archive is ~2.5KB. The crash is deterministic on every attempt.\n\n### Impact\n\nDenial of service. Any application or tool that extracts untrusted tar archives crashes from a single small file. This includes npm (which uses node-tar to extract packages), CI/CD pipelines, file upload processors, and backup tools. The crash cannot be caught by application-level error handling.","published":"2026-07-08T15:25:09.519Z","modified":"2026-08-12T03:51:23.212840260Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":{"score":0.00644,"percentile":0.49251,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"tar","fixedVersion":"7.5.18"}],"fix":{"url":"https://github.com/isaacs/node-tar/commit/e02a4e9e013c4be95302e2eb2047a942b883c27b","label":"isaacs/node-tar@e02a4e9"},"references":[{"type":"WEB","url":"https://github.com/isaacs/node-tar/releases/tag/v7.5.18"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59871.json"},{"type":"ADVISORY","url":"https://github.com/isaacs/node-tar/security/advisories/GHSA-w8wr-v893-vjvp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59871"},{"type":"FIX","url":"https://github.com/isaacs/node-tar/commit/e02a4e9e013c4be95302e2eb2047a942b883c27b"},{"type":"PACKAGE","url":"https://github.com/isaacs/node-tar"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:23.212840260Z"}}