How severe is CVE-2026-59874?

No CVSS score has been assigned to CVE-2026-59874 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-59874?

CVE-2026-59874 affects the following packages: tar (npm). Ecosystems affected: npm.

How do I fix CVE-2026-59874?

Update tar to 7.5.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59874 is resolved across your whole dependency graph.

How do I detect CVE-2026-59874 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 CVE-2026-59874 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 CVE-2026-59874?

O3 pinpoints whether CVE-2026-59874 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 CVE-2026-59874 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-59874 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 type of vulnerability is CVE-2026-59874?

CVE-2026-59874 is classified as CWE-835 (CWE-835). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-59874 published, and has it been updated?

CVE-2026-59874 was published on July 8, 2026 and was last updated on August 12, 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

Not in CISA KEV

CVE-2026-59874

Fix: isaacs/node-tar@9e78bf0

CVE-2026-59874 is a CWE-835 vulnerability in tar. O3 Security confirms whether CVE-2026-59874 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

node-tar: Negative tar entry size causes infinite loop in archive replace

Also known asGHSA-8x88-c5mf-7j5w

Published

Jul 8, 2026

Updated

Aug 12, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Aug 12, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

📦tar

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

node-tar is a tar archive manipulation library for Node.js. Prior to 7.5.18, tar.replace accepts a checksum-valid tar header with a negative base-256 encoded entry size, causing the archive scanner to make no progress while repeatedly parsing the same header. This issue is fixed in version 7.5.18.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`tar`	all versions	7.5.18

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 7.5.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59874 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 CVE-2026-59874 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 CVE-2026-59874. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2026-59874 in your dependencies?

O3 detects CVE-2026-59874 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works