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Maven

GHSA-wx5j-54mm-rqqq

MEDIUM

HTTP request smuggling in netty

Also known asCVE-2021-43797
Published
Dec 9, 2021
Updated
Mar 13, 2026
Affected
3 pkgs
Patched
1 / 3
Exploits
None indexed

EPSS Exploitation Probability

via FIRST.org ↗
2.7%probability of exploitation in next 30 days
Lower Risk84th percentile+2.30%
0.00%1.14%2.28%3.43%0.2%2.7%Dec 25Apr 26Jun 26

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

3 pkgs affected
io.netty:netty-codec-httporg.jboss.netty:nettyio.netty:netty

Real-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

Netty currently just skips control chars when these are present at the beginning / end of the header name. We should better fail fast as these are not allowed by the spec and could lead to HTTP request smuggling.

Failing to do the validation might cause netty to "sanitize" header names before it forward these to another remote system when used as proxy. This remote system can't see the invalid usage anymore and so not do the validation itself.

Affected Packages

3 total 1 fixed
EcosystemPackageVulnerable rangeFix
Mavenio.netty:netty-codec-http4.0.0&&< 4.1.71.Final4.1.71.Final
Mavenorg.jboss.netty:nettyall versionsNo fix
Mavenio.netty:nettyall versionsNo fix

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-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.

  2. Fix

    Update io.netty:netty-codec-http to 4.1.71.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wx5j-54mm-rqqq is resolved across your whole dependency graph.

  3. 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.

  4. How O3 protects you

    O3 pinpoints whether GHSA-wx5j-54mm-rqqq 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-wx5j-54mm-rqqq. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact Netty currently just skips control chars when these are present at the beginning / end of the header name. We should better fail fast as these are not allowed by the spec and could lead to HTTP request smuggling. Failing to do the validation might cause netty to "sanitize" header names before it forward these to another remote system when used as proxy. This remote system can't see the invalid usage anymore and so not do the validation itself.
O3 Security · Impact-Aware SCA

Is GHSA-wx5j-54mm-rqqq in your dependencies?

O3 detects GHSA-wx5j-54mm-rqqq across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.