CVE-2026-19204
WebSocket unknown-opcode allows large allocation causing JVM heap exhaustion (DoS).
Is CVE-2026-19204 being exploited?
Not confirmed. CVE-2026-19204 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.29% probability of exploitation in the next 30 days.
How severe is CVE-2026-19204?
CVE-2026-19204 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-19204?
Yes. A fix has been recorded for CVE-2026-19204. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-19204 affect?
CVE-2026-19204 affects Eclipse Jetty (WebSocket, auto-fragmentation enabled). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-19204?
Upgrade Jetty to patched release or disable WebSocket auto-fragmentation.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote denial-of-service: crafted WebSocket frame with unknown opcode and huge declared length triggers large allocation, causing JVM OOM and service crash.
Patch when possible
- affected>= 12.1.0 and <= 12.1.11
- affected>= 12.0.0 and <= 12.0.37
- affected>= 11.0.0 and <= 11.0.31
- affected>= 10.0.0 and <= 10.0.31
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.