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Vulnerability · Published Jun 12, 2026 · Assigned by GitHub_M

CVE-2026-48059Netty HAProxy: Unbalanced Reference Count in Nested PP2_TYPE_SSL TLV Parsing Leads to Memory Exhaustion

High 7.5

In plain English

A high-severity memory leak in netty from netty. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.6%top 49.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12nettyno fix listedDEBIAN-CVE-2026-48059
Debian:13nettyno fix listedDEBIAN-CVE-2026-48059
Debian:14nettyno fix listedDEBIAN-CVE-2026-48059
Mavenio.netty:netty-codec-haproxy4.1.135.FinalGHSA-h2qv-fj59-j46j
Mavenio.netty:netty-codec-haproxy4.2.15.FinalGHSA-h2qv-fj59-j46j
Ubuntu:25.10nettyno fix listedUBUNTU-CVE-2026-48059
Ubuntu:26.10nettyno fix listedUBUNTU-CVE-2026-48059

Affected products (as reported)

VendorProductVersions
netty netty >= 4.2.0.Final, < 4.2.15.Final< 4.1.135.Final

Weakness: CWE-401, CWE-1286 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References