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MEDIUM severity

GHSA-jwp9-9v96-94mx

MEDIUM

GHSA-jwp9-9v96-94mx is a medium-severity (CVSS 5.5) CWE-59 vulnerability in decompress. O3 Security confirms whether GHSA-jwp9-9v96-94mx is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

decompress allows arbitrary hardlink creation during archive extraction

Also known asCVE-2026-39243
Published
Jul 10, 2026
Updated
Aug 13, 2026
Affected
1 pkg
Patched
None yet
Exploits
None indexed
Exploitation data as of Aug 13, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
📦decompress

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

decompress before 4.2.2 allows arbitrary hardlink creation during archive extraction, enabling file read disclosure and file corruption. When processing hardlink entries (type === 'link'), the x.linkname field from the archive is passed directly to fs.link() without validation (index.js line 113). An attacker can craft an archive with a hardlink entry whose linkname is an absolute path to any file on the same filesystem. This creates a hardlink inside the extraction directory that shares the same inode as the target file, enabling both reading and overwriting the original file's content. Hardlinks are limited to files on the same filesystem and cannot target directories.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
📦npmdecompressall versionsNo fix

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for decompress. 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.

  2. Remediation status

    No patched version of decompress has shipped for GHSA-jwp9-9v96-94mx yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    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.

  4. How O3 protects you

    O3 pinpoints whether GHSA-jwp9-9v96-94mx 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 GHSA-jwp9-9v96-94mx. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

decompress before 4.2.2 allows arbitrary hardlink creation during archive extraction, enabling file read disclosure and file corruption. When processing hardlink entries (type === 'link'), the x.linkname field from the archive is passed directly to fs.link() without validation (index.js line 113). An attacker can craft an archive with a hardlink entry whose linkname is an absolute path to any file on the same filesystem. This creates a hardlink inside the extraction directory that shares the same inode as the target file, enabling both reading and overwriting the original file's content. Hardl
O3 Security · Impact-Aware SCA

Is GHSA-jwp9-9v96-94mx in your dependencies?

O3 detects GHSA-jwp9-9v96-94mx across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

GHSA-jwp9-9v96-94mx: decompress… | O3 Security