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Fencer Vulns
high 7.5

CVE-2026-5680 json

Undertow-core: undertow: denial of service via websocket permessage-deflate processing

published 2026-08-27 2 mo ago modified 2026-11-04 4 d ago also EUVD-2026-67086

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 65%
public exploits
0
none known

Summary

A flaw was found in Undertow. A remote attacker could exploit this vulnerability by sending specially crafted WebSocket messages with permessage-deflate negotiated. This could lead to excessive memory consumption due to the PerMessageDeflateFunction.largerBuffer() method using exponential doubling, resulting in a Denial of Service (DoS) for the affected application.

Patch / fix

  • Red Hat Red Hat JBoss Enterprise Application Platform 8.1.8.GA 2.3.26.SP3-redhat-00001
  • Red Hat Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 10 0:1.2.7-1.redhat_00002.1.el10eap, 0:1.85.0-1.redhat_00001.1.el10eap, 0:2.0.5-1.Final_redhat_00001.1.el10eap, 0:2.1.0-1.redhat_00001.1.el10eap, 0:2.2.0-1.Final_redhat_00001.1.el10eap, 0:2.18.9-1.redhat_00003.1.el10eap, 0:2.40.0-8.redhat_00024.1.el10eap, 0:3.0.1-1.Final_redhat_00001.1.el10eap, 0:3.0.22-1.Final_redhat_00001.1.el10eap, 0:3.1.0-1.Final_redhat_00001.1.el10eap, 0:3.6.3-1.Final_redhat_00001.1.el10eap, 0:4.0.5-1.redhat_00001.1.el10eap, 0:4.0.7-4.redhat_00001.1.el10eap, 0:4.1.5-5.redhat_00008.1.el10eap, 0:4.1.7-1.SP1_redhat_00001.1.el10eap, 0:5.0.31-1.SP2_redhat_00001.1.el10eap, 0:5.1.0-1.Final_redhat_00001.1.el10eap, 0:6.6.54-1.Final_redhat_00001.1.el10eap, 0:7.4.0-1.Final_redhat_00001.1.el10eap, 0:801.8.0-1.GA_redhat_00001.1.el10eap
  • Red Hat Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8 0:1.2.7-1.redhat_00002.1.el8eap, 0:1.85.0-1.redhat_00001.1.el8eap, 0:2.0.5-1.Final_redhat_00001.1.el8eap, 0:2.1.0-1.redhat_00001.1.el8eap, 0:2.2.0-1.Final_redhat_00001.1.el8eap, 0:2.18.9-1.redhat_00003.1.el8eap, 0:2.40.0-8.redhat_00024.1.el8eap, 0:3.0.1-1.Final_redhat_00001.1.el8eap, 0:3.0.22-1.Final_redhat_00001.1.el8eap, 0:3.1.0-1.Final_redhat_00001.1.el8eap, 0:3.6.3-1.Final_redhat_00001.1.el8eap, 0:4.0.5-1.redhat_00001.1.el8eap, 0:4.0.7-4.redhat_00001.1.el8eap, 0:4.1.5-5.redhat_00008.1.el8eap, 0:4.1.7-1.SP1_redhat_00001.1.el8eap, 0:5.0.31-1.SP2_redhat_00001.1.el8eap, 0:5.1.0-1.Final_redhat_00001.1.el8eap, 0:6.6.54-1.Final_redhat_00001.1.el8eap, 0:7.4.0-1.Final_redhat_00001.1.el8eap, 0:801.8.0-1.GA_redhat_00001.1.el8eap
  • Red Hat Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9 0:1.2.7-1.redhat_00002.1.el9eap, 0:1.85.0-1.redhat_00001.1.el9eap, 0:2.0.5-1.Final_redhat_00001.1.el9eap, 0:2.1.0-1.redhat_00001.1.el9eap, 0:2.2.0-1.Final_redhat_00001.1.el9eap, 0:2.18.9-1.redhat_00003.1.el9eap, 0:2.40.0-8.redhat_00024.1.el9eap, 0:3.0.1-1.Final_redhat_00001.1el9eap, 0:3.0.22-1.Final_redhat_00001.1.el9eap, 0:3.1.0-1.Final_redhat_00001.1.el9eap, 0:3.6.3-1.Final_redhat_00001.1.el9eap, 0:4.0.5-1.redhat_00001.1.el9eap, 0:4.0.7-4.redhat_00001.1.el9eap, 0:4.1.5-5.redhat_00008.1.el9eap, 0:4.1.7-1.SP1_redhat_00001.1.el9eap, 0:5.0.31-1.SP2_redhat_00001.1.el9eap, 0:5.1.0-1.Final_redhat_00001.1.el9eap, 0:6.6.54-1.Final_redhat_00001.1.el9eap, 0:7.4.0-1.Final_redhat_00001.1.el9eap, 0:801.8.0-1.GA_redhat_00001.1.el9eap
  • eap8-jaxb jboss enterprise application platform 8.1 4.0.7-4.redhat_00001.1.el10eap
  • eap8-txw2 jboss enterprise application platform 8.1 4.0.7-4.redhat_00001.1.el10eap
  • eap8-xsom jboss enterprise application platform 8.1 4.0.7-4.redhat_00001.1.el10eap
  • eap8-log4j jboss enterprise application platform 8.1 2.25.4-1.redhat_00003.1.el10eap
  • eap8-netty jboss enterprise application platform 8.1 4.1.136-1.Final_redhat_00001.1.el10eap
  • eap8-rngom jboss enterprise application platform 8.1 4.0.7-4.redhat_00001.1.el10eap
  • eap8-slf4j jboss enterprise application platform 8.1 2.0.18-1.redhat_00001.1.el10eap
  • eap8-neethi jboss enterprise application platform 8.1 3.2.2-1.redhat_00001.1.el10eap

red hat advisories RHSA-2026:70230RHSA-2026:70229RHSA-2026:70228

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-5680 updated cvss 7.5

undertow-core: Undertow: Denial of Service via WebSocket permessage-deflate processing

  • Red Hat build of Apache Camel for Spring Boot 4 undertow-core
    affected: workaround, no fix available
  • Red Hat Data Grid 8 undertow-core Red Hat JBoss Enterprise Application Platform 7 undertow-core
    affected: workaround, no fix planned “Will not fix”
  • Red Hat JBoss Enterprise Application Platform 8 undertow-core
    affected: workaround, no fix available
  • Red Hat JBoss Enterprise Application Platform Expansion Pack undertow-core, undertow-core-2.3.10.Final.jar
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat Process Automation 7 undertow-core Red Hat Single Sign-On 7 undertow-core
    affected: workaround, no fix planned “Will not fix”
  • Red Hat JBoss EAP 8.1 for RHEL 8 eap8-jaxb 4.0.7-4.redhat_00001.1.el8eap, eap8-txw2 4.0.7-4.redhat_00001.1.el8eap, eap8-xsom 4.0.7-4.redhat_00001.1.el8eap, eap8-rngom 4.0.7-4.redhat_00001.1.el8eap, eap8-log4j 2.25.4-1.redhat_00003.1.el8eap, eap8-neethi 3.2.2-1.redhat_00001.1.el8eap, +101 more
    fixed: vendor fix RHSA-2026:70228
  • Red Hat JBoss EAP 8.1 for RHEL 9 eap8-jaxb 4.0.7-4.redhat_00001.1.el9eap, eap8-txw2 4.0.7-4.redhat_00001.1.el9eap, eap8-xsom 4.0.7-4.redhat_00001.1.el9eap, eap8-rngom 4.0.7-4.redhat_00001.1.el9eap, eap8-log4j 2.25.4-1.redhat_00003.1.el9eap, eap8-neethi 3.2.2-1.redhat_00001.1.el9eap, +101 more
    fixed: vendor fix RHSA-2026:70229
  • Red Hat JBoss EAP 8.1 for RHEL 10 eap8-jaxb 4.0.7-4.redhat_00001.1.el10eap, eap8-txw2 4.0.7-4.redhat_00001.1.el10eap, eap8-xsom 4.0.7-4.redhat_00001.1.el10eap, eap8-rngom 4.0.7-4.redhat_00001.1.el10eap, eap8-log4j 2.25.4-1.redhat_00003.1.el10eap, eap8-neethi 3.2.2-1.redhat_00001.1.el10eap, +100 more
    fixed: vendor fix RHSA-2026:70230
show 4 more
  • Red Hat JBoss Enterprise Application Platform 8.1.8.GA undertow-core 2.3.26.SP3-redhat-00001
    fixed: vendor fix RHSA-2026:70277
  • Red Hat build of Apache Camel - HawtIO 4 undertow-core
    not affected: vulnerable code not in execute path
  • Red Hat Enterprise Linux 8 resteasy, resteasy-javadoc Red Hat Enterprise Linux 9 resteasy, pki-resteasy-core, pki-resteasy-client, pki-resteasy-jackson2-provider, pki-resteasy-servlet-initializer
    not affected: component not present
  • Red Hat Enterprise Linux 10 moditect Red Hat Fuse 7 undertow-core Red Hat JBoss Enterprise Application Platform 8.1.8.GA pom.xml, aesh 2.4, c3 0.6.4, d3 7.4.3, he 1.2.0, lr 1.4.2, +1868 more Red Hat JBoss Enterprise Application Platform Expansion Pack undertow-core-2.3.18.Final.jar, undertow-core-2.3.23.SP3-redhat-00001.jar
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

1.10% chance of exploitation in the next 30 days, higher than 65% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Red Hat Red Hat JBoss Enterprise Application Platform 8.1.8.GA
  • Red Hat Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 10
  • Red Hat Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8
  • Red Hat Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9
  • Red Hat Red Hat build of Apache Camel for Spring Boot 4
  • Red Hat Red Hat build of Apache Camel - HawtIO 4
  • Red Hat Red Hat Data Grid 8
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Fuse 7
  • Red Hat Red Hat JBoss Enterprise Application Platform 7
  • Red Hat Red Hat JBoss Enterprise Application Platform 8
  • Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack
  • Red Hat Red Hat Process Automation 7
  • Red Hat Red Hat Single Sign-On 7

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.