How severe is CVE-2026-48059?

No CVSS score has been assigned to CVE-2026-48059 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-48059?

CVE-2026-48059 affects the following packages: io.netty:netty-codec-haproxy (Maven), io.netty:netty-codec-haproxy (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-48059?

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 CVE-2026-48059 is resolved across your whole dependency graph.

How do I detect CVE-2026-48059 in my Maven dependencies?

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.

How do I mitigate CVE-2026-48059 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2026-48059?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-48059 can be triaged on real exposure rather than presence alone.

Is CVE-2026-48059 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-48059 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-48059?

CVE-2026-48059 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 49th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-48059?

CVE-2026-48059 is classified as CWE-401 (CWE-401), CWE-1286 (CWE-1286). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-48059 published, and has it been updated?

CVE-2026-48059 was published on June 12, 2026 and was last updated on September 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

Not in CISA KEV

CVE-2026-48059 — netty-codec-haproxy

CVE-2026-48059 is a 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.

Netty HAProxy: Unbalanced Reference Count in Nested PP2_TYPE_SSL TLV Parsing Leads to Memory Exhaustion

Also known asGHSA-h2qv-fj59-j46j

Published

Jun 12, 2026

Updated

Sep 20, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Sep 23, 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 CVE-2026-48059.

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs49th percentile — riskier than 49% of all scored CVEsHighest risk

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.

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

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.netty:netty-codec-haproxy`	≥ 4.2.0.Final&&< 4.2.15.Final	4.2.15.Final`io.netty:netty-codec-haproxy:4.2.15.Final`
☕Maven	`io.netty:netty-codec-haproxy`	all versions	4.1.135.Final`io.netty:netty-codec-haproxy:4.1.135.Final`

Detection & mitigation playbook

Open-source dependency

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.
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 CVE-2026-48059 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 CVE-2026-48059 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-48059. 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.

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…

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 ELS on RHEL 7	`eap7-activemq-artemis-0:2.16.0-22.redhat_00057.1.el7eap`	RHSA-2026:53644

Frequently Asked Questions

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 (

O3 Security · Impact-Aware SCA

Is CVE-2026-48059 in your dependencies?

O3 Security finds CVE-2026-48059 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works