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HIGH severity

Netty HAProxy: Unbalanced Reference Count in Nested PP2_TYPE_SSL TLV Parsing Leads to Memory ExhaustionGHSA-h2qv-fj59-j46j

HIGH

GHSA-h2qv-fj59-j46j is a high-severity (CVSS 7.5) CWE-401 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.

Also known asCVE-2026-48059
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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-h2qv-fj59-j46j.

EPSS Exploitation Probability

via FIRST.org ↗
0.6%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs51th percentile — riskier than 51% of all scored CVEsHighest risk
0.09%0.52%0.95%1.38%0.6%0.6%Jul 26Oct 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected
☕io.netty:netty-codec-haproxy☕io.netty:netty-codec-haproxy

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

Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, the HAProxy PROXY protocol v2 codec in netty leaks native or heap memory on every connection when a client sends a syntactically valid header containing nested PP2_TYPE_SSL TLVs (type-length-value records) at depth two or greater. The leak occurs on the successful parse path — no exception is thrown, the message fires downstream, the decoder removes itself, and the application releases the HAProxyMessage normally. Yet the underlying cumulation buffer (a pooled, potentially direct ByteBuf allocated by the channel) remains permanently pinned. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenio.netty:netty-codec-haproxy≥ 4.2.0.Final&&< 4.2.15.Final4.2.15.Finalio.netty:netty-codec-haproxy:4.2.15.Final
☕Mavenio.netty:netty-codec-haproxyall versions4.1.135.Finalio.netty:netty-codec-haproxy:4.1.135.Final

Affected Products

1 product · 2 configurations
Application
nettynetty
≥ 4.2.0 && < 4.2.15
range

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-haproxy, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. 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-h2qv-fj59-j46j 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.

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.

Red HatImportant

This is an Important flaw in the Netty HAProxy PROXY protocol v2 codec, which can lead to a denial of service. A remote attacker can trigger a memory leak by sending a specially crafted HAProxy PROXY protocol v2 header with deeply nested SSL TLV records, causing resource exhaustion in affected Red Hat products that…

Workaround published by Red Hat
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-h2qv-fj59-j46j (CC BY 4.0)
ProductFixed inAdvisory
Cryostat 4 on RHEL 9cryostat/cryostat-reports-rhel9:4.2.0-13RHSA-2026:48151
Red Hat AMQ Broker 7.14.1netty-codec-haproxyRHSA-2026:66488
Red Hat Build of Apache Camel 3.33.2.SP1io.netty/netty-codec-haproxy:4.1.135.Final-redhat-00001RHSA-2026:26586
Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16netty-codec-haproxyRHSA-2026:37390
Red Hat build of Keycloak 26.4.13see advisoryRHSA-2026:30049
Red Hat build of Keycloak 26.6.4see advisoryRHSA-2026:30083
Red Hat build of Quarkus 3.27.4.SP1io.netty/netty-codec-haproxy:4.1.135.Final-redhat-00001RHSA-2026:26018
Red Hat build of Quarkus 3.33.2.SP1io.netty/netty-codec-haproxy:4.1.135.Final-redhat-00001RHSA-2026:26017

Frequently Asked Questions

### Impact The HAProxy PROXY protocol v2 codec in netty leaks native or heap memory on every connection when a client sends a syntactically valid header containing nested `PP2_TYPE_SSL` TLVs (type-length-value records) at depth two or greater. The leak occurs on the successful parse path — no exception is thrown, the message fires downstream, the decoder removes itself, and the application releases the `HAProxyMessage` normally. Yet the underlying cumulation buffer (a pooled, potentially direct `ByteBuf` allocated by the channel) remains permanently pinned.
O3 Security · Impact-Aware SCA

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