GHSA-mg66-mrh9-m8jx
HIGHGHSA-mg66-mrh9-m8jx is a high-severity (CVSS 7.5) vulnerability in next. O3 Security confirms whether GHSA-mg66-mrh9-m8jx is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Next.js vulnerable to Denial of Service via connection exhaustion in applications using Cache Components
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
nextnpmDescription
Impact
Applications using Partial Prerendering through the Cache Components feature can be vulnerable to connection exhaustion through crafted POST requests to a server action. In affected configurations, a malicious request can trigger a request-body handling deadlock that leaves connections open for an extended period, consuming file descriptors and server capacity until legitimate users are denied service.
Fix
We now treat the header used for resuming Partial Prerendered requests as an internal-only header and strip it from untrusted incoming requests. This header should never be accepted directly from external clients.
Workarounds
If you cannot upgrade immediately, block requests that would be handled by Next.js if they contain the Next-Resume header at the edge.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | next | ≥ 15.0.0&&< 15.5.16 | 15.5.16 |
| 📦npm | next | ≥ 16.0.0&&< 16.2.5 | 16.2.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for next. 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 next to 15.5.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mg66-mrh9-m8jx 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-mg66-mrh9-m8jx 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-mg66-mrh9-m8jx. 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-mg66-mrh9-m8jx in your dependencies?
O3 detects GHSA-mg66-mrh9-m8jx across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.