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CVE-2026-23950 high CVSS 8.8

Vulnerability in Isaacs (CVE-2026-23950)

Summary

Vulnerability in Isaacs (CVE-2026-23950). Data can be tampered with by attackers. Exploitable via PathReservations.

Original description

The description as published by the source.

node-tar,a Tar for Node.js, has a race condition vulnerability in versions up to and including 7.5.3. This is due to an incomplete handling of Unicode path collisions in the path-reservations system. On case-insensitive or normalization-insensitive filesystems (such as macOS APFS, In which it has been tested), the library fails to lock colliding paths (e.g., ß and ss), allowing them to be processed in parallel. This bypasses the library's internal concurrency safeguards and permits Symlink Poisoning attacks via race conditions. The library uses a PathReservations system to ensure that metadata checks and file operations for the same path are serialized. This prevents race conditions where one entry might clobber another concurrently. This is a Race Condition which enables Arbitrary File Overwrite. This vulnerability affects users and systems using node-tar on macOS (APFS/HFS+). Because of using NFD Unicode normalization (in which ß and ss are different), conflicting paths do not have their order properly preserved under filesystems that ignore Unicode normalization (e.g., APFS (in which ß causes an inode collision with ss)). This enables an attacker to circumvent internal parallelization locks (PathReservations) using conflicting filenames within a malicious tar archive. The patch in version 7.5.4 updates path-reservations.js to use a normalization form that matches the target filesystem's behavior (e.g., NFKD), followed by first `toLocaleLowerCase('en…

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

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-2026-23950 has been found in Isaacs.
Attackers can target a specific entry point like PathReservations over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 8.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Isaacs CVE-2026-23950" on the vendor's site.

CVE-2026-23950 (Isaacs) — CWE-176 / CVSS v3 8.8
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: PathReservations / NFD / NFKD / SymbolicLink
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-176) exists in Isaacs. Attackers reach the vulnerable code path via PathReservations without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of Isaacs. Attack surface: PathReservations / NFD / NFKD / SymbolicLink.

🔥 Severity

Severity: High (CVSS 8.8/10). Data can be tampered with by attackers.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ 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 'Isaacs' . 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 'Isaacs' . | 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 Isaacs 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
    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。

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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