GHSA-79cf-xcqc-c78w
MEDIUMGHSA-79cf-xcqc-c78w is a medium-severity (CVSS 5.3) CWE-749 vulnerability in webpack-dev-server. O3 Security confirms whether GHSA-79cf-xcqc-c78w is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins
Exploitation Status
No confirmed exploitation observed yet
- 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-79cf-xcqc-c78w.
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-79cf-xcqc-c78w 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 0 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
When webpack-dev-server is running on a non-HTTPS origin (the default), cross-origin requests from malicious websites can load the dev server's JavaScript bundles via <script> tags. The fix introduced in v5.2.1 (CVE-2025-30359) relied on Sec-Fetch-Mode and Sec-Fetch-Site request headers to block these requests, but browsers only send these headers for potentially trustworthy origins. Over plain HTTP, the headers are absent and the check is bypassed.
An attacker who knows the dev server's host, port, and output path can exfiltrate all module source code by intercepting the webpack runtime's module registration.
This does not affect Chrome 142+ (and other Chromium-based browsers) due to local network access restrictions.
Patches
Patched in webpack-dev-server >= 5.2.4 by setting Cross-Origin-Resource-Policy: same-origin on responses.
Workarounds
Run the dev server with HTTPS enabled (--https or server.type: 'https' in config).
Resources
- GHSA-4v9v-hfq4-rm2v (CVE-2025-30359) - original vulnerability
- GHSA-9jgg-88mc-972h (CVE-2025-30360) - prior bypass
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | webpack-dev-server | all versions | 5.2.4 |
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 5.2.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-79cf-xcqc-c78w 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-79cf-xcqc-c78w 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-79cf-xcqc-c78w. 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-79cf-xcqc-c78w in your dependencies?
O3 detects GHSA-79cf-xcqc-c78w across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.