GHSA-wm47-8v5p-wjpj is a medium-severity (CVSS 5.9) CWE-444 vulnerability in io.netty:netty-codec-http2. O3 Security confirms whether GHSA-wm47-8v5p-wjpj is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Possible request smuggling in HTTP/2 due missing validation
Real-World Exposure
io.netty:netty-codec-http2☕org.jboss.netty:netty☕io.netty:nettyReal-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
Impact
If a Content-Length header is present in the original HTTP/2 request, the field is not validated by Http2MultiplexHandler as it is propagated up. This is fine as long as the request is not proxied through as HTTP/1.1.
If the request comes in as an HTTP/2 stream, gets converted into the HTTP/1.1 domain objects (HttpRequest, HttpContent, etc.) via Http2StreamFrameToHttpObjectCodec and then sent up to the child channel's pipeline and proxied through a remote peer as HTTP/1.1 this may result in request smuggling.
In a proxy case, users may assume the content-length is validated somehow, which is not the case. If the request is forwarded to a backend channel that is a HTTP/1.1 connection, the Content-Length now has meaning and needs to be checked.
An attacker can smuggle requests inside the body as it gets downgraded from HTTP/2 to HTTP/1.1. A sample attack request looks like:
POST / HTTP/2
:authority:: externaldomain.com
Content-Length: 4
asdfGET /evilRedirect HTTP/1.1
Host: internaldomain.com
Users are only affected if all of this is true:
HTTP2MultiplexCodecorHttp2FrameCodecis usedHttp2StreamFrameToHttpObjectCodecis used to convert to HTTP/1.1 objects- These HTTP/1.1 objects are forwarded to another remote peer.
Patches
This has been patched in 4.1.60.Final
Workarounds
The user can do the validation by themselves by implementing a custom ChannelInboundHandler that is put in the ChannelPipeline behind Http2StreamFrameToHttpObjectCodec.
References
Related change to workaround the problem: https://github.com/Netflix/zuul/pull/980
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-codec-http2 | ≥ 4.0.0&&< 4.1.60.Final | 4.1.60.Final |
| ☕Maven | org.jboss.netty:netty | all versions | No fix |
| ☕Maven | io.netty:netty | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-http2. 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.netty:netty-codec-http2 to 4.1.60.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wm47-8v5p-wjpj 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-wm47-8v5p-wjpj 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-wm47-8v5p-wjpj. 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-wm47-8v5p-wjpj in your dependencies?
O3 detects GHSA-wm47-8v5p-wjpj across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.