CVE-2026-73566 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in tar. O3 Security confirms whether CVE-2026-73566 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
node-tar: Uncontrolled recursion in mapHas/filesFilter allows uncatchable stack-overflow DoS via crafted long-path tar with member selection
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
tarnpmDescription
node-tar is a tar archive manipulation library for Node.js. Prior to 7.5.21, node-tar's filesFilter in src/list.ts uses the recursive mapHas helper to walk an archive entry path upward with path.dirname() and no segment cap when tar.t(...) or tar.x(...) receives a non-empty member-selection list. A crafted GNU L or PAX x long-path header with thousands of slash-separated segments reaches this.filter(entry.path, entry) in Parser[CONSUMEHEADER] in src/parse.ts before Unpack[CHECKPATH] applies maxDepth, causing an uncatchable RangeError stack overflow that terminates asynchronous and streaming Node.js consumers. This issue is fixed in version 7.5.21.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | tar | all versions | 7.5.21 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tar. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update tar to 7.5.21 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73566 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-73566 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-73566. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-73566 in your dependencies?
O3 detects CVE-2026-73566 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.