CVE-2026-19204CWE-770CWE-789

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…

High · published September 7, 2026

CVSS v4.0
8.7
EPSS
—
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
8.7 · HIGH
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
EPSS
Not scored
Weaknesses
CWE-770 · Allocation of Resources Without Limits or Throttling; CWE-789 · Memory Allocation with Excessive Size Value
Published
2026-09-07T10:19Z
Timeline
  • 07 SEP 10:19Z
    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…
    cvelistv5