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CVE-2026-73566 high CVSS 7.5

Vulnerability in tar (CVE-2026-73566)

Summary

Vulnerability in tar (CVE-2026-73566). Risk of unauthorized operations or information disclosure. Exploitable via tar. Mitigation: upgrade to 7.5.21 or later.

Original description

The description as published by the source.

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

Una…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-73566 has been found in tar.
Attackers can target a specific entry point like tar over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade tar to 7.5.21 or later.
If unsure, ask your IT team or search "tar CVE-2026-73566" on the vendor's site.

CVE-2026-73566 (tar) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: tar / mapHas / filesFilter / maxMetaEntrySize
Patched: 7.5.21 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-400) exists in tar. Attackers reach the vulnerable code path via tar without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of tar. Attack surface: tar / mapHas / filesFilter / maxMetaEntrySize.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 7.5.21.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'tar' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'tar' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で tar を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade tar to 7.5.21

    ステージング環境で 7.5.21 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

npm tar
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.5.21"}]}]

References

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