CVE-2026-89044 Other in netty
Attackers can perform HTTP request smuggling by exploiting improper Transfer-Encoding validation in the Netty library, potentially bypassing security controls.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89044?
CVE-2026-89044 is a medium-severity vulnerability in Netty Netty, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Netty versions 4.1.133.Final through 4.1.137.Final and 4.2.13.Final through 4.2.17.Final fail to properly validate the final transfer coding in the Transfer-Encoding header, allowing attackers to smuggle requests by using malformed encoding declarations. Attackers can split Transfer-Encoding headers across multiple lines or use values like 'chunked, xchunked' to bypass validation and decode messages as chunked when the final coding is not chunked, enabling request smuggling attacks.
Weakness: CWE-444
Which versions are affected by CVE-2026-89044?
It affects 1 product.
Products include Netty Netty.
How do I fix CVE-2026-89044?
Upgrade to a fixed version.
Is CVE-2026-89044 being exploited?
There is no known exploitation of CVE-2026-89044 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-DD54267, CLEANSTART-2026-HA92776, CLEANSTART-2026-JI34331, CLEANSTART-2026-JM40588, CLEANSTART-2026-KP79659, CLEANSTART-2026-OZ38695 and 5 more.