CVE-2026-44891 Netty: Denial of Service via Unbounded Headers in StompSubframeDecoder
Attackers can cause denial of service in STOMP servers by sending unbounded headers, exhausting memory in the Netty library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-44891?
CVE-2026-44891 is a high-severity denial of service vulnerability in Netty Netty, published on 17 Jul 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 4.1.136.Final and 4.2.16.Final, io.netty.handler.codec.stomp.StompSubframeDecoder fails to limit the total number of headers or their cumulative size per frame, and the maxLineLength parameter only restricts individual header lines. An attacker can send a large number of short headers that are accumulated in memory inside DefaultStompHeadersSubframe until the JVM throws an OutOfMemoryError, causing denial of service for servers exposing a STOMP endpoint based on StompSubframeDecoder. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
Which versions are affected by CVE-2026-44891?
4 open source packages ship an affected version, including io.netty:netty-codec-stomp. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
io.netty:netty-codec-stomp Maven | All versions | 4.1.136.Final |
io.netty:netty-codec-stomp Maven | All versions | 4.1.136.Final |
io.netty:netty-codec-stomp Maven | From 4.2.0.Alpha1 | 4.2.16.Final |
io.netty:netty-codec-stomp Maven | From 4.2.0.Alpha1 | 4.2.16.Final |
Products include Netty Netty.
How do I fix CVE-2026-44891?
Upgrade io.netty:netty-codec-stomp to a fixed version for your release line: 4.1.136.Final or 4.2.16.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-2026-44891 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44891 exists.
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-WN14447, CLEANSTART-2026-XB76941, CLEANSTART-2026-YM67930, DEBIAN-CVE-2026-44891, ECHO-7228-fe24-aad3, GHSA-vhch-2wf3-m8rp and 11 more.