node-tar: Uncontrolled recursion in mapHas/filesFilter allows uncatchable stack-overflow DoS via crafted long-path tar with member selection

Overview

Summary

node-tar (npm tar) contains an uncontrolled-recursion stack-exhaustion DoS in the internal mapHas helper used by filesFilter. When a consumer calls tar.t(...) or tar.x(...) with a non-empty member-selection list, node-tar installs a filter that closes over the recursive mapHas (src/list.ts:33-44). mapHas walks an entry path upward one path.dirname() call per recursion with no segment cap. A single crafted tar with a GNU-L (or PAX-x) long-path header can deliver a path of tens of thousands of /-separated segments (up to maxMetaEntrySize = 1 MiB). The recursion overflows the call stack, throwing an uncatchable RangeError that terminates the Node process on async/streaming consumers.

Root Cause

filesFilter (src/list.ts:27-51) is installed whenever a caller passes a member-selection list (src/list.ts:119-122, src/extract.ts:55-57). Its filter is invoked at src/parse.ts:253 (entry.ignore = entry.ignore || !this.filter(entry.path, entry)) inside Parser[CONSUMEHEADER] — and crucially outside the only try/catch in that method (which wraps new Header at src/parse.ts:179-183). mapHas recurses once per path segment with no depth limit. The Unpack maxDepth guard (src/unpack.ts:342, in [CHECKPATH]) only runs on the 'entry' event, which fires after CONSUMEHEADER has already invoked the filter — so the stack overflows before any depth guard executes. tar.t (list) has no maxDepth at all.

Impact

Unauthenticated, remotely-triggerable denial of service: a ~188-byte gzip (≈26 KB tar) crashes any service that lists or extracts selected members from an untrusted archive (package registries, CI artifact/cache restore, upload processors). On async (await tar.t(...)/tar.x(...)) and streaming/pipe consumers the RangeError escapes the promise as an uncaughtException and terminates the process — standard defensive try/catch around the async call does NOT prevent it. (The synchronous API is catchable; the async/stream paths — the dominant server pattern — are not.)

Proof of Concept

// Build a tar whose single entry has a GNU-L long path of ~12,000 "a/" segments (~26 KB),
// gzip it (≈188 bytes), then have a consumer list/extract with member selection:
const tar = require('tar');
await tar.t({ file: 'evil.tar.gz', gzip: true }, ['some-member']); // -> RangeError, process exit

Empirically reproduced on Node v24.18.0 against built dist/commonjs of node-tar 7.5.20: 188-byte gzip → 26,112-byte tar (12,000 segments) → uncaught RangeError: Maximum call stack size exceeded → process exit. A control run with no member-selection list (filter not installed) parses cleanly (exit 0), isolating mapHas as the sole cause.

Attack Chain

1. Entry. Attacker crafts a tar with a GNU L (or PAX x) long-path header whose body is "a/"×~12000 (~26 KB), followed by a normal file entry.
   • Guard: maxMetaEntrySize caps the meta body at 1 MiB (src/parse.ts:241).
   • Bypass proof: 26 KB ≪ 1 MiB → accepted (verified: 26 KB archive parsed up to the filter).
2. Trigger. Victim service calls tar.t({file},[sel]) or tar.x({file,cwd},[sel]) (member selection — a documented, common API).
   • Guard: Unpack.maxDepth (default 1024) at src/unpack.ts:342; decompression-ratio guard.
   • Bypass proof: maxDepth lives in [CHECKPATH] on the 'entry' event, which fires after CONSUMEHEADER's filter call — the crash occurs before it (extract exits 1 with default maxDepth). tar.t has no maxDepth. Ratio is ~139× (trivial); no total-bytes cap applies to the uncompressed meta body.
3. Sink. this.filter(entry.path) → mapHas recurses once per / segment (src/list.ts:39).
   • Guard: try/catch in CONSUMEHEADER.
   • Bypass proof: the only try/catch wraps new Header (src/parse.ts:179-183); the this.filter(...) call at src/parse.ts:253 is outside it. The RangeError propagates out of the stream write/'data' path → uncaught exception (verified: process.on('uncaughtException') fires; async await+try/catch does NOT intercept).
4. Impact. Node process termination; a 188-byte gzip crashes any consumer that lists/extracts selected members from untrusted archives.

Bypass Evidence

• mapHas recursion is member-name-independent: the crash fires even when the requested members do not match the malicious entry path — the attacker only needs the consumer to use member selection.
• Standalone mapHas overflows at 20k–30k segments; on the real streaming path (atop write → CONSUMECHUNK → CONSUMEHEADER → filter) it crashes at ≤8k segments (finder's ~12k estimate is accurate for the reachable path).
• Control (no member list → no filter) parses cleanly (exit 0), isolating mapHas.

Affected Versions

<= 7.5.20 (npm tar). mapHas present verbatim on tag v7.5.20 (latest GitHub release and npm dist-tag latest); no segment/depth cap in src/list.ts or the CONSUMEHEADER filter path; HEAD == 7.5.20, no unreleased fix.

Suggested Fix

Rewrite mapHas iteratively (walk dirname in a while loop with a segment/visited cap), or enforce a hard path-segment limit in Header/Parser independent of maxMetaEntrySize, applied before any per-entry filter runs.

Dedup Note

Distinct from CVE-2024-28863 / GHSA-f5x3-32g6-qm9j "lack of folders depth validation" (that bounds mkdir recursion during extraction via maxDepth in Unpack[CHECKPATH] on the 'entry' event — a different sink, code path, and fix; runs after the filter and does not apply to tar.t). Also distinct from the PAX NUL/numeric-path crash advisories (improper-input-to-fs / type confusion, not recursion) and the gzip-bomb advisory (resource exhaustion on disk writes). None touch list.ts/filesFilter/mapHas or require member selection.

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Reported by zx (Jace) — GitHub: @manus-use

Affected packages

• tar <= 7.5.20

Remediation

Upgrade to a patched release:

• tar 7.5.21