How severe is GHSA-83g3-92jg-28cx?

GHSA-83g3-92jg-28cx has a CVSS score of 7.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-83g3-92jg-28cx?

GHSA-83g3-92jg-28cx affects the following packages: tar (npm). Ecosystems affected: npm.

How do I fix GHSA-83g3-92jg-28cx?

Update tar to 7.5.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-83g3-92jg-28cx is resolved across your whole dependency graph.

How do I detect GHSA-83g3-92jg-28cx in my npm dependencies?

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

How do I mitigate GHSA-83g3-92jg-28cx if there is no patch (or I can't update yet)?

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.

How does O3 Security protect against GHSA-83g3-92jg-28cx?

O3 pinpoints whether GHSA-83g3-92jg-28cx is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-83g3-92jg-28cx actively exploited in the wild?

No public exploit code has been indexed for GHSA-83g3-92jg-28cx yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-83g3-92jg-28cx?

GHSA-83g3-92jg-28cx has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 20th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-83g3-92jg-28cx?

GHSA-83g3-92jg-28cx is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-83g3-92jg-28cx published, and has it been updated?

GHSA-83g3-92jg-28cx was published on February 18, 2026 and was last updated on February 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

GHSA-83g3-92jg-28cx

HIGH

Arbitrary File Read/Write via Hardlink Target Escape Through Symlink Chain in node-tar Extraction

Also known asCVE-2026-26960

Published

Feb 18, 2026

Updated

Feb 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk20th percentile+0.28%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

tarnpm

104.8Mdownloads / week

Description

Summary

tar.extract() in Node tar allows an attacker-controlled archive to create a hardlink inside the extraction directory that points to a file outside the extraction root, using default options.

This enables arbitrary file read and write as the extracting user (no root, no chmod, no preservePaths).

Severity is high because the primitive bypasses path protections and turns archive extraction into a direct filesystem access primitive.

Details

The bypass chain uses two symlinks plus one hardlink:

a/b/c/up -> ../..
a/b/escape -> c/up/../..
exfil (hardlink) -> a/b/escape/<target-relative-to-parent-of-extract>

Why this works:

Linkpath checks are string-based and do not resolve symlinks on disk for hardlink target safety.
- See STRIPABSOLUTEPATH logic in:
  - ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:255
  - ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:268
  - ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:281
Hardlink extraction resolves target as path.resolve(cwd, entry.linkpath) and then calls fs.link(target, destination).
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:566
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:567
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:703
Parent directory safety checks (mkdir + symlink detection) are applied to the destination path of the extracted entry, not to the resolved hardlink target path.
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:617
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:619
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/mkdir.js:27
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/mkdir.js:101

As a result, exfil is created inside extraction root but linked to an external file. The PoC confirms shared inode and successful read+write via exfil.

PoC

hardlink.js Environment used for validation:

Node: v25.4.0
tar: 7.5.7
OS: macOS Darwin 25.2.0
Extract options: defaults (tar.extract({ file, cwd }))

Steps:

Prepare/locate a tar module. If require('tar') is not available locally, set TAR_MODULE to an absolute path to a tar package directory.
Run:

TAR_MODULE="$(cd '../tar-audit-setuid - CVE/node_modules/tar' && pwd)" node hardlink.js

Expected vulnerable output (key lines):

same_inode=true
read_ok=true
write_ok=true
result=VULNERABLE

Interpretation:

same_inode=true: extracted exfil and external secret are the same file object.
read_ok=true: reading exfil leaks external content.
write_ok=true: writing exfil modifies external file.

Impact

Vulnerability type:

Arbitrary file read/write via archive extraction path confusion and link resolution.

Who is impacted:

Any application/service that extracts attacker-controlled tar archives with Node tar defaults.
Impact scope is the privileges of the extracting process user.

Potential outcomes:

Read sensitive files reachable by the process user.
Overwrite writable files outside extraction root.
Escalate impact depending on deployment context (keys, configs, scripts, app data).

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`tar`	all versions	7.5.8

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tar. 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.
Fix
Update tar to 7.5.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-83g3-92jg-28cx is resolved across your whole dependency graph.
Workarounds
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.
How O3 protects you
O3 pinpoints whether GHSA-83g3-92jg-28cx 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-83g3-92jg-28cx. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary `tar.extract()` in Node `tar` allows an attacker-controlled archive to create a hardlink inside the extraction directory that points to a file outside the extraction root, using default options. This enables **arbitrary file read and write** as the extracting user (no root, no chmod, no `preservePaths`). Severity is high because the primitive bypasses path protections and turns archive extraction into a direct filesystem access primitive. ### Details The bypass chain uses two symlinks plus one hardlink: 1. `a/b/c/up -> ../..` 2. `a/b/escape -> c/up/../..` 3. `exfil` (hardlink)

O3 Security · Impact-Aware SCA

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