GHSA-m28w-2pqf-7qgj is a medium-severity (CVSS 5.3) Improper Input Validation vulnerability in webpack-dev-server. O3 Security confirms whether GHSA-m28w-2pqf-7qgj is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header
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
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.
How urgent is this, really
GHSA-m28w-2pqf-7qgj plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 369,023 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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.
webpack-dev-servernpmDescription
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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | webpack-dev-server | all versions | 5.2.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for webpack-dev-server. 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 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.
How O3 protects you
O3 pinpoints whether GHSA-m28w-2pqf-7qgj 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-m28w-2pqf-7qgj. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-m28w-2pqf-7qgj in your dependencies?
O3 detects GHSA-m28w-2pqf-7qgj across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.