How severe is GHSA-x6fg-f45m-jf5q?

GHSA-x6fg-f45m-jf5q has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-x6fg-f45m-jf5q?

GHSA-x6fg-f45m-jf5q affects the following packages: semver (npm). Ecosystems affected: npm.

How do I fix GHSA-x6fg-f45m-jf5q?

Update semver to 4.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x6fg-f45m-jf5q is resolved across your whole dependency graph.

How do I detect GHSA-x6fg-f45m-jf5q in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for semver. 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-x6fg-f45m-jf5q 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-x6fg-f45m-jf5q?

O3 pinpoints whether GHSA-x6fg-f45m-jf5q 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-x6fg-f45m-jf5q actively exploited in the wild?

No public exploit code has been indexed for GHSA-x6fg-f45m-jf5q 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 GHSA-x6fg-f45m-jf5q?

GHSA-x6fg-f45m-jf5q is classified as CWE-399 (CWE-399). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-x6fg-f45m-jf5q published, and has it been updated?

GHSA-x6fg-f45m-jf5q was published on October 24, 2017 and was last updated on March 4, 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-x6fg-f45m-jf5q

HIGH

GHSA-x6fg-f45m-jf5q is a high-severity (CVSS 7.5) CWE-399 vulnerability in semver. O3 Security confirms whether GHSA-x6fg-f45m-jf5q is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Regular Expression Denial of Service in semver

Also known asCVE-2015-8855

Published

Oct 24, 2017

Updated

Mar 4, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

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

semvernpm

835.9Mdownloads / week

Description

Versions 4.3.1 and earlier of semver are affected by a regular expression denial of service vulnerability when extremely long version strings are parsed.

Recommendation

Update to version 4.3.2 or later

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`semver`	≥ 1.0.4&&< 4.3.2	4.3.2

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for semver. 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 semver to 4.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x6fg-f45m-jf5q 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-x6fg-f45m-jf5q 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-x6fg-f45m-jf5q. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Versions 4.3.1 and earlier of `semver` are affected by a regular expression denial of service vulnerability when extremely long version strings are parsed. ## Recommendation Update to version 4.3.2 or later

O3 Security · Impact-Aware SCA

Is GHSA-x6fg-f45m-jf5q in your dependencies?

O3 detects GHSA-x6fg-f45m-jf5q 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