{"id":"CVE-2026-106073","kind":"vulnerability","aliases":["CVE-2026-106073"],"related":[],"title":"Node.js: Permission Model lets fs.realpathSync probe paths outside allowed reads","description":"A flaw in Node.js Permission Model filesystem enforcement leaves `fs.realpathSync()` without the required read permission checks. This is an incomplete fix of CVE-2026-21715, which only covered `fs.realpathSync.native()`.\n\nAs a result, code running under `--permission` with restricted `--allow-fs-read` can still use `fs.realpathSync()` to check file existence, resolve symlink targets, and enumerate filesystem paths outside of permitted directories.\n\nThis vulnerability affects Node.js **26.x**, **24.x**, and **22.x**.","summary":"Node.js's Permission Model does not apply read checks to fs.realpathSync(), so code run with --permission and a restricted --allow-fs-read can still check whether files exist, resolve symlink targets and list paths outside its allowed directories. This is an incomplete fix of CVE-2026-21715, which only covered fs.realpathSync.native().","severity":"low","cvss":3.3,"epss":0.00159,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["node.js","poc-public","runtime","self-hosted"],"not_affected_if":["default-config","no-permission-model"],"how_to_check":"- Run `node --version` and compare against the fixed releases listed in the advisory; affected lines are 22.x, 24.x and 26.x.\n- Look for `--permission` or `--experimental-permission` together with `--allow-fs-read` in process start scripts, Dockerfiles or service units.","fix":"- Upgrade Node.js to a patched release for your line (version numbers unknown from the sources; check the Node.js security release notes).\n- Until patched, do not rely on --allow-fs-read alone to confine untrusted code that can call fs.realpathSync.","status":"open","published_at":"2026-10-23T17:17:20+00:00","first_seen_at":"2026-10-23T21:57:34+00:00","triaged_at":"2026-10-25T04:45:49+00:00","updated_at":"2026-10-25T12:38:50+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-10-25T04:45:49Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Node.js to a patched release for your line (version numbers unknown from the sources; check the Node.js security release notes).\n- Until patched, do not rely on --allow-fs-read alone to confine untrusted code that can call fs.realpathSync.","reach":"local","title":"Node.js: Permission Model lets fs.realpathSync probe paths outside allowed reads","impact":"low","summary":"Node.js's Permission Model does not apply read checks to fs.realpathSync(), so code run with --permission and a restricted --allow-fs-read can still check whether files exist, resolve symlink targets and list paths outside its allowed directories. This is an incomplete fix of CVE-2026-21715, which only covered fs.realpathSync.native().","category":"runtime","nicknames":[],"who_cares":["node.js","self-hosted"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Attacker maps filesystem paths outside permitted directories, reading file metadata and symlink targets","analyst_note":"Confirm the fixed Node.js versions for 22.x, 24.x and 26.x from the Node.js security release notes; the sources do not list them.","how_to_check":"- Run `node --version` and compare against the fixed releases listed in the advisory; affected lines are 22.x, 24.x and 26.x.\n- Look for `--permission` or `--experimental-permission` together with `--allow-fs-read` in process start scripts, Dockerfiles or service units.","needs_analyst":true,"not_affected_if":["default-config","no-permission-model"],"who_is_affected":"Only applications that run Node.js with the Permission Model enabled (--permission) and a restricted --allow-fs-read list are exposed, since that is the only case where the missing check matters. Teams running Node.js without the permission flag, or relying on OS-level isolation, can skip it.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"low"},"cost_usd":0.000685,"input_tokens":3475,"output_tokens":675,"severity_before":"low"},"analyst_status":null,"analyst_note":null,"search":"'-106073':13A,16A '-2026':12A,15A,71B,100C '-21715':72B,101C '22':147C '24':144C '26':142C 'affect':140C 'allow':9A,45B,62B,116C 'allow-fs-read':44B,115C 'appli':31B 'check':33B,50B,92C,124C 'code':37B,109C 'cover':75B,104C 'cve':11A,14A,70B,99C 'directori':63B,137C 'enforc':84C 'enumer':131C 'exist':53B,126C 'file':52B,125C 'filesystem':83C,132C 'fix':68B,97C 'flaw':78C 'fs':46B,117C 'fs.realpathsync':5A,35B,86C,122C 'fs.realpathsync.native':76B,105C 'host':24B 'incomplet':67B,96C 'leav':85C 'let':4A 'list':58B 'model':3A,28B,82C 'node.js':1A,17B,25B,80C,141C 'outsid':8A,60B,134C 'path':7A,59B,133C 'permiss':2A,27B,40B,81C,91C,112C 'permit':136C 'poc':19B 'poc-publ':18B 'probe':6A 'public':20B 'read':10A,32B,47B,90C,118C 'requir':89C 'resolv':54B,127C 'restrict':43B,114C 'result':108C 'run':38B,110C 'runtim':21B 'self':23B 'self-host':22B 'still':49B,120C 'symlink':55B,128C 'target':56B,129C 'use':121C 'vulner':139C 'whether':51B 'without':87C 'x':143C,145C,148C","nicknames":[],"mitigations":[],"who_affected":"Only applications that run Node.js with the Permission Model enabled (--permission) and a restricted --allow-fs-read list are exposed, since that is the only case where the missing check matters. Teams running Node.js without the permission flag, or relying on OS-level isolation, can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-23T17:17:20+00:00","kev":null,"cvss_vector":"CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","cvss_by":"support@hackerone.com","poc_count":1,"sources":[{"source":"nvd","external_id":"CVE-2026-106073","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-106073","severity":null,"published_at":"2026-10-23T17:17:20+00:00","modified_at":"2026-10-23T19:42:24+00:00","first_seen_at":"2026-10-23T21:57:34+00:00","fetched_at":"2026-10-23T22:29:03+00:00","note":null},{"source":"github-poc","external_id":"CompleteTech-LLC/node-cve-2026-106073-check","url":"https://github.com/CompleteTech-LLC/node-cve-2026-106073-check","severity":null,"published_at":"2026-10-23T23:48:48+00:00","modified_at":null,"first_seen_at":"2026-10-23T23:55:02+00:00","fetched_at":"2026-10-23T23:55:02+00:00","note":null},{"source":"epss","external_id":"CVE-2026-106073","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-106073","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-25T12:38:50+00:00","fetched_at":"2026-10-25T12:38:50+00:00","note":null}],"documents":[{"id":2239,"url":"https://github.com/CompleteTech-LLC/node-cve-2026-106073-check","title":"CompleteTech-LLC/node-cve-2026-106073-check","kind":"poc","source":"github","text":"Standalone defensive checker project for CVE-2026-106073: Node.js: Permission Model realpathSync read bypass. One exploit per repository; implementation pending.\n\nstars 0","published_at":"2026-10-23T23:48:48+00:00","relation":"poc","confidence":null,"note":"0 stars"}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}