CVE-2026-19204Network attack vector

JVM heap exhaustion via unvalidated WebSocket length

Published Sep 7, 2026 · Updated Sep 8, 2026

Denial of service in affected Eclipse Jetty releases allows remote attackers to exhaust JVM heap via a crafted WebSocket frame. With auto-fragmentation enabled, an unknown opcode bypasses maximum-frame-size handling, so payload memory is allocated from the declared length before opcode validation. A reachable WebSocket endpoint and auto-fragmentation are required; successful exploitation can crash the JVM and interrupt hosted services.

CVSS severity8.7
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected Eclipse Jetty releases allows remote attackers to exhaust JVM heap via a crafted WebSocket frame. With auto-fragmentation enabled, an unknown opcode bypasses maximum-frame-size handling, so payload memory is allocated from the declared length before opcode validation. A reachable WebSocket endpoint and auto-fragmentation are required; successful exploitation can crash the JVM and interrupt hosted services.

The record

CVE
CVE-2026-19204
Published
Sep 7, 2026
Updated
Sep 8, 2026
Vendor
The Eclipse Foundation
Product
Eclipse Jetty
Classifications
CWE-770, CWE-789, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.0 <=10.0.31
  2. Affected versionversion=11.0.0 <=11.0.31
  3. Affected versionversion=12.0.0 <=12.0.37
  4. Affected versionversion=12.1.0 <=12.1.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Eclipse Foundation · Eclipse Jettyversion=10.0.0 <=10.0.31; version=11.0.0 <=11.0.31; version=12.0.0 <=12.0.37; version=12.1.0 <=12.1.11

Published CVSS scores

8.7Eclipse FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-789Memory Allocation with Excessive Size Value
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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