{"id":"GHSA-w8wr-v893-vjvp","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 -\u003e ReadEntry -\u003e 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) =\u003e { /* never reached */ })\n  .on('warn', (code, msg) =\u003e { /* 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.","aliases":["CVE-2026-59871"],"modified":"2026-07-20T22:00:20.210593544Z","published":"2026-07-20T21:53:14Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-07-20T21:53:14Z","nvd_published_at":"2026-07-08T16:16:33Z","cwe_ids":["CWE-704"],"severity":"MODERATE"},"references":[{"type":"WEB","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":"WEB","url":"https://github.com/isaacs/node-tar/commit/e02a4e9e013c4be95302e2eb2047a942b883c27b"},{"type":"PACKAGE","url":"https://github.com/isaacs/node-tar"},{"type":"WEB","url":"https://github.com/isaacs/node-tar/releases/tag/v7.5.18"}],"affected":[{"package":{"name":"tar","ecosystem":"npm","purl":"pkg:npm/tar"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"7.5.18"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 7.5.17","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-w8wr-v893-vjvp/GHSA-w8wr-v893-vjvp.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}