How severe is GHSA-m28w-2pqf-7qgj?

GHSA-m28w-2pqf-7qgj has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-m28w-2pqf-7qgj?

GHSA-m28w-2pqf-7qgj affects the following packages: webpack-dev-server (npm). Ecosystems affected: npm.

How do I fix GHSA-m28w-2pqf-7qgj?

Update webpack-dev-server to 5.2.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m28w-2pqf-7qgj is resolved across your whole dependency graph.

How do I detect GHSA-m28w-2pqf-7qgj in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for webpack-dev-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-m28w-2pqf-7qgj 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.

Is GHSA-m28w-2pqf-7qgj actively exploited in the wild?

No public exploit code has been indexed for GHSA-m28w-2pqf-7qgj 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-m28w-2pqf-7qgj?

GHSA-m28w-2pqf-7qgj has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 43th 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-m28w-2pqf-7qgj?

GHSA-m28w-2pqf-7qgj is classified as Improper Input Validation (CWE-20), CWE-248 (CWE-248). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-m28w-2pqf-7qgj published, and has it been updated?

GHSA-m28w-2pqf-7qgj was published on July 20, 2026 and was last updated on September 10, 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

MEDIUM severity

webpack-dev-server vulnerable to denial of service via a malformed Host or Origin headerGHSA-m28w-2pqf-7qgj

MEDIUMFix: webpack/webpack-dev-server#5699

GHSA-m28w-2pqf-7qgj is a medium-severity (CVSS 5.3) Improper Input Validation vulnerability in webpack-dev-server. A fix is available for webpack-dev-server — see the affected versions and patch details below.

Also known asCVE-2026-14631

Published

Jul 20, 2026

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-m28w-2pqf-7qgj.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk+0.11%

Lower risk than most CVEs43th percentile — riskier than 43% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-m28w-2pqf-7qgj by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

12Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

webpack-dev-servernpm

9.5Mdownloads / week

Description

Impact

An unauthenticated peer that can reach the webpack-dev-server process can terminate it by sending either a normal HTTP request with a malformed Host header, or a WebSocket upgrade to the default /ws endpoint with a malformed Origin header. The malformed header triggers an uncaught exception in the host-validation path and crashes the dev server process.

Patches

Fixed in webpack-dev-server 5.2.6 by treating malformed Host and Origin header values as invalid rather than throwing (see PR #5699).

Workarounds

Keep the dev server bound to localhost (the default) and do not expose it to untrusted networks.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`webpack-dev-server`	all versions	5.2.6`npm install webpack-dev-server@5.2.6`

Affected Products

1 product · 1 configurations

Application

webpack-dev-serverwebpack.js

< 5.2.6

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for webpack-dev-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update webpack-dev-server to 5.2.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m28w-2pqf-7qgj 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.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

webpack-dev-server is a development-time tool used to serve files during local frontend development and is not started or executed in production deployments. While the package may appear in SBOM manifests due to its presence in build-stage node_modules, the webpack-dev-server process is not running in shipped…

Workaround published by Red Hat

webpack-dev-server should never be exposed to untrusted networks. By default, it binds to localhost only. Users who run webpack-dev-server during development should ensure it remains bound to localhost and upgrade to version 5.2.6 or later, which fixes the malformed header handling.

Source: Red Hat security advisory for GHSA-m28w-2pqf-7qgj (CC BY 4.0)

Frequently Asked Questions

### Impact An unauthenticated peer that can reach the `webpack-dev-server` process can terminate it by sending either a normal HTTP request with a malformed `Host` header, or a WebSocket upgrade to the default `/ws` endpoint with a malformed `Origin` header. The malformed header triggers an uncaught exception in the host-validation path and crashes the dev server process. ### Patches Fixed in `webpack-dev-server` 5.2.6 by treating malformed `Host` and `Origin` header values as invalid rather than throwing (see [PR #5699](https://github.com/webpack/webpack-dev-server/pull/5699)). ### Workar