CVE-2026-50560 Netty susceptible to HTTP/2 Reset Attack with different on-the-wire signature
Netty is vulnerable to a HTTP/2 Reset Attack causing denial of service when handling large header sizes, requiring an upgrade to patched versions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-50560?
CVE-2026-50560 is a medium-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, Netty HTTP/2 max header size handling produces an attack similar to HTTP/2 Rapid Reset. There is a setting in the http2 specification called `SETTINGS_MAX_HEADER_LIST_SIZE`. When a client sends that setting to Netty, it appears that Netty will behave as follows: read the request; proxy the request to the origin; attempt to produce a response; and create an exception while writing the headers for the response. Functionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature. Versions 4.1.135.Final and 4.2.15.Final patch the issue.
Weakness: CWE-770
Which versions are affected by CVE-2026-50560?
4 open source packages ship an affected version, including io.netty:netty-codec-http2. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
io.netty:netty-codec-http2 Maven | All versions | 4.1.135.Final |
io.netty:netty-codec-http2 Maven | All versions | 4.1.135.Final |
io.netty:netty-codec-http2 Maven | From 4.2.0.Final | 4.2.15.Final |
io.netty:netty-codec-http2 Maven | From 4.2.0.Final | 4.2.15.Final |
Products include Netty Netty.
How do I fix CVE-2026-50560?
Upgrade io.netty:netty-codec-http2 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-2026-50560 being exploited?
There is no known exploitation of CVE-2026-50560 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-GI68379, CLEANSTART-2026-IP93838, CLEANSTART-2026-JY64777, CLEANSTART-2026-PG06501, CLEANSTART-2026-XZ02009, DEBIAN-CVE-2026-50560 and 78 more.