CVE-2020-5404
MEDIUMCVE-2020-5404 is a medium-severity (CVSS 5.9) CWE-522 vulnerability in io.projectreactor.netty:reactor-netty-http. O3 Security confirms whether CVE-2020-5404 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Insufficiently Protected Credentials in Reactor Netty
Blast Radius
io.projectreactor.netty:reactor-netty-http☕io.projectreactor.netty:reactor-netty-httpReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
The HttpClient from Reactor Netty, versions 0.9.x prior to 0.9.5, and versions 0.8.x prior to 0.8.16, may be used incorrectly, leading to a credentials leak during a redirect to a different domain. In order for this to happen, the HttpClient must have been explicitly configured to follow redirects.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.projectreactor.netty:reactor-netty-http | ≥ 0.9.0&&< 0.9.5 | 0.9.5 |
| ☕Maven | io.projectreactor.netty:reactor-netty-http | ≥ 0.8.0&&< 0.8.16 | 0.8.16 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.projectreactor.netty:reactor-netty-http. 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 io.projectreactor.netty:reactor-netty-http to 0.9.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-5404 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 CVE-2020-5404 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 CVE-2020-5404. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2020-5404 in your dependencies?
O3 detects CVE-2020-5404 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.