GHSA-f256-j965-7f32
MEDIUMGHSA-f256-j965-7f32 is a medium-severity (CVSS 5.9) CWE-444 vulnerability in io.netty:netty-codec-http2. O3 Security confirms whether GHSA-f256-j965-7f32 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 of content-length
Blast Radius
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
The content-length header is not correctly validated if the request only use a single Http2HeaderFrame with the endStream set to to true. This could lead to request smuggling if the request is proxied to a remote peer and translated to HTTP/1.1
This is a followup of https://github.com/netty/netty/security/advisories/GHSA-wm47-8v5p-wjpj which did miss to fix this one case.
Patches
This was fixed as part of 4.1.61.Final
Workarounds
Validation can be done by the user before proxy the request by validating the header.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-codec-http2 | ≥ 4.0.0&&< 4.1.61.Final | 4.1.61.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 4.1.61.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f256-j965-7f32 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-f256-j965-7f32 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-f256-j965-7f32. 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-f256-j965-7f32 in your dependencies?
O3 detects GHSA-f256-j965-7f32 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.