CVE-2026-19204 Denial of service in Eclipse Jetty
Attackers can exhaust JVM heap memory via crafted WebSocket frames when auto-fragmentation is enabled, causing denial of service in Jetty servers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-19204?
CVE-2026-19204 is a high-severity denial of service vulnerability in Eclipse Jetty, published on 7 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A client may send a WebSocket frame with an unknown opcode and a very large declared payload length, causing Jetty to attempt a large memory allocation and potentially exhaust the JVM heap.
This occurs when auto-fragmentation is enabled, as unknown opcodes bypass the normal maximum frame size handling and payload allocation occurs before the opcode is validated.
Which versions are affected by CVE-2026-19204?
How do I fix CVE-2026-19204?
Apply the vendor's patch.
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-2026-19204 being exploited?
There is no known exploitation of CVE-2026-19204 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-SV46004, CLEANSTART-2026-TT31497, CLEANSTART-2026-VO81158, DEBIAN-CVE-2026-19204, GHSA-85fq-fc5f-7j7g, GHSA-w753-5ffq-99wr and 1 more.