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Vulnerability record · CVE-2026-19204 · published 7 September 2026

CVE-2026-19204: Allocation without limits vulnerability

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.

8.7 CVSS 4.0 High EPSS 0.31% · top 78.6% CWE-770 · Allocation without limitsCWE-789 · CWE-789 Deferred
8.7CVSS 4.0 base score
0.31%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
1References
8 Sep 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/jetty/jetty.project/security/advisories/GHSA-85fq-fc5f-7j7g

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-19204), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.