GHSA-cc37-9q2j-3hfv — netty-codec-haproxy
HIGHGHSA-cc37-9q2j-3hfv is a high-severity (CVSS 7.5) CWE-703 vulnerability in io.netty:netty-codec-haproxy. A fix is available for io.netty:netty-codec-haproxy — see the affected versions and patch details below.
Netty: HAProxy SSL TLV parsing leaks retained slice on invalid TLV length
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-cc37-9q2j-3hfv.
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.
How urgent is this, really
GHSA-cc37-9q2j-3hfv plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
io.netty:netty-codec-haproxy☕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
Netty is a network application framework for development of protocol servers and clients. In netty-codec-haproxy prior to versions 4.1.135.Final and 4.2.15.Final, when decoding a PP2_TYPE_SSL TLV, HAProxyMessage.readNextTLV() first calls header.retainedSlice(header.readerIndex(), length) and only then reads the 1-byte client field and 4-byte verify field. If the attacker sets the TLV length below 5, the subsequent readByte/readInt throws IndexOutOfBoundsException. HAProxyMessageDecoder only catches HAProxyProtocolException around this call, so the IOOBE propagates and the retained slice on the pooled cumulation buffer is never released. Versions 4.1.135.Final and 4.2.15.Final patch the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-codec-haproxy | ≥ 4.2.0.Final&&< 4.2.15.Final | 4.2.15.Finalio.netty:netty-codec-haproxy:4.2.15.Final |
| ☕Maven | io.netty:netty-codec-haproxy | all versions | 4.1.135.Finalio.netty:netty-codec-haproxy:4.1.135.Final |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.netty:netty-codec-haproxy to 4.2.15.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cc37-9q2j-3hfv 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-cc37-9q2j-3hfv can be triaged on real exposure rather than presence alone.
Tailored to GHSA-cc37-9q2j-3hfv. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This flaw is rated as Important because a remote, unauthenticated attacker can trigger a denial of service in applications utilizing `netty-codec-haproxy`. By sending a specially crafted HAProxy message with a malformed SSL TLV header, an attacker can cause an `IndexOutOfBoundsException`, leading to unreleased memory…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for GHSA-cc37-9q2j-3hfv (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Cryostat 4 on RHEL 9 | cryostat/cryostat-reports-rhel9:4.2.0-13 | RHSA-2026:48151 |
| Red Hat AMQ Broker 7.14.1 | netty-codec-haproxy | RHSA-2026:66488 |
| Red Hat Build of Apache Camel 3.33 for Quarkus 3.33.2.SP1 | netty-codec-haproxy | RHSA-2026:26586 |
| Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16 | netty-codec-haproxy | RHSA-2026:37390 |
| Red Hat build of Quarkus 3.27.4.SP1 | netty-codec-haproxy | RHSA-2026:26018 |
| Red Hat build of Quarkus 3.33.2.SP1 | netty-codec-haproxy | RHSA-2026:26017 |
| Red Hat Data Grid 8.6.2 | netty-codec-haproxy | RHSA-2026:41951 |
| Red Hat JBoss Enterprise Application Platform 7.4.25 | io.netty/netty-codec-haproxy:4.1.135.Final-redhat-00001 | RHSA-2026:53806 |
Frequently Asked Questions
Is GHSA-cc37-9q2j-3hfv in your dependencies?
O3 Security finds GHSA-cc37-9q2j-3hfv across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.