CVE-2026-48059 Netty HAProxy: Unbalanced Reference Count in Nested PP2_TYPE_SSL TLV Parsing Leads to Memory Exhaustion
Attackers can cause memory exhaustion in Netty HAProxy codec by sending nested SSL TLVs, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-48059?
CVE-2026-48059 is a high-severity denial of service vulnerability in Netty Netty, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Which versions are affected by CVE-2026-48059?
4 open source packages ship an affected version, including io.netty:netty-codec-haproxy. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
io.netty:netty-codec-haproxy Maven | All versions | 4.1.135.Final |
io.netty:netty-codec-haproxy Maven | All versions | 4.1.135.Final |
io.netty:netty-codec-haproxy Maven | From 4.2.0.Final | 4.2.15.Final |
io.netty:netty-codec-haproxy Maven | From 4.2.0.Final | 4.2.15.Final |
Products include Netty Netty.
How do I fix CVE-2026-48059?
Upgrade io.netty:netty-codec-haproxy to a fixed version for your release line: 4.1.135.Final or 4.2.15.Final.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-48059 being exploited?
There is no known exploitation of CVE-2026-48059 in the wild and no public exploit code.
Other vulnerabilities in Netty Netty
- CVE-2026-75595 Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext
- CVE-2026-75596 Netty: Fragmented ClientHello records trigger quadratic pre-handshake reassembly in default SNI parsing
- CVE-2026-59901 Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang
- CVE-2026-55851 Netty codec-haproxy: Signed-Byte Sentinel Collision in HAProxyMessageDecoder Leads to Unbounded Memory Exhaustion
- CVE-2026-56745 Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion
Sources
Also known as CLEANSTART-2026-BD80531, CLEANSTART-2026-HH77101, CLEANSTART-2026-PJ95856, DEBIAN-CVE-2026-48059, ECHO-fd53-f198-b51a, GHSA-h2qv-fj59-j46j and 29 more.