Sign in Sign up
JA · EN · FR
SecPulse
Categories
CVE-2026-59871 medium CVSS 5.3

Vulnerability in tar (CVE-2026-59871)

Summary

Vulnerability in tar (CVE-2026-59871). Risk of unauthorized operations or information disclosure. Exploitable via pax.ts. Mitigation: upgrade to 7.5.18 or later.

Original description

The description as published by the source.

Summary

A 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.

Details

In 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.

This number flows through Header -> ReadEntry -> Unpack.CHECKPATH, where normalizeWindowsPath(entry.path).split('/') throws a TypeError because numbers don't have .split().

The throw is synchronous during event emission and bypasses all error handling:

  • strict: false does not help
  • 'error' event handlers do not catch it
  • 'warn' handlers do not catch it
  • The TypeError propagates through the event emitter stack as an uncaughtException

Directory, 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.

PoC

Create a tar archive with a PAX extended header containing an all-digit path:

PAX header body: "18 path=12345\n"
Entry type: Directory (type '5')

Extract it:

const tar = require('tar');

// All of these crash wi…

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-2026-59871 has been found in tar.
Attackers can target a specific entry point like pax.ts over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade tar to 7.5.18 or later.
If unsure, ask your IT team or search "tar CVE-2026-59871" on the vendor's site.

CVE-2026-59871 (tar) — CWE-704 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: pax.ts / parseKV / path / linkpath
Patched: 7.5.18 — 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-704) exists in tar. Attackers reach the vulnerable code path via pax.ts without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of tar. Attack surface: pax.ts / parseKV / path / linkpath.

🔥 Severity

Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 7.5.18.

🛡️ 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 7.5.18

    ステージング環境で 7.5.18 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":"7.5.18"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

We use cookies for analytics and ad measurement. This setting applies to all Game co., Ltd. sites. Details