GHSA-gpvr-g6gh-9mc2
MEDIUMGHSA-gpvr-g6gh-9mc2 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in express. O3 Security confirms whether GHSA-gpvr-g6gh-9mc2 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
No Charset in Content-Type Header in express
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
expressnpmDescription
Vulnerable versions of express do not specify a charset field in the content-type header while displaying 400 level response messages. The lack of enforcing user's browser to set correct charset, could be leveraged by an attacker to perform a cross-site scripting attack, using non-standard encodings, like UTF-7.
Recommendation
For express 3.x, update express to version 3.11 or later. For express 4.x, update express to version 4.5 or later.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | express | all versions | 3.11.0 |
| 📦npm | express | ≥ 4.0.0&&< 4.5.0 | 4.5.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for express. 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 express to 3.11.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gpvr-g6gh-9mc2 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-gpvr-g6gh-9mc2 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-gpvr-g6gh-9mc2. 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-gpvr-g6gh-9mc2 in your dependencies?
O3 detects GHSA-gpvr-g6gh-9mc2 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.