GHSA-fx2c-96vj-985v
MEDIUMHAProxyMessageDecoder Stack Exhaustion DoS
EPSS Exploitation Probability
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
io.netty:netty-codec-haproxyReal-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
A StackOverflowError can be raised when parsing a malformed crafted message due to an infinite recursion.
Patches
Users should upgrade to 4.1.86.Final.
Workarounds
There is no workaround, except using a custom HaProxyMessageDecoder.
References
When parsing a TLV with type = PP2_TYPE_SSL, the value can be again a TLV with type = PP2_TYPE_SSL and so on. The only limitation of the recursion is that the TLV length cannot be bigger than 0xffff because it is encoded in an unsigned short type. Providing a TLV with a nesting level that is large enough will lead to raising of a StackOverflowError. The StackOverflowError will be caught if HAProxyMessageDecoder is used as part of Netty’s ChannelPipeline, but using it directly without the ChannelPipeline will lead to a thrown exception / crash.
For more information
If you have any questions or comments about this advisory:
- Open an issue in netty
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-codec-haproxy | all versions | 4.1.86.Final |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
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-haproxy. 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-haproxy to 4.1.86.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fx2c-96vj-985v 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-fx2c-96vj-985v 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-fx2c-96vj-985v. 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-fx2c-96vj-985v in your dependencies?
O3 detects GHSA-fx2c-96vj-985v across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.