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Fencer Intel
high 7.5

CVE-2026-77791 json

Apache Tomcat: DoS via busy wait during WebSocket close

published last mo. modified last mo. also BIT-tomcat-2026-77791 , EUVD-2026-85229

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
0
none known

Summary

Uncontrolled Resource Consumption vulnerability in Apache Tomcat during sending of WebSocket close message enabled a DoS attack.

This issue affects Apache Tomcat: from 11.0.0-M5 through 11.0.25, from 10.1.8 through 10.1.59, from 9.0.74 through 9.0.121.

The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.88 through 8.5.100. Other unsupported versions may also be affected.

Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.

Patch / fix

  • bitnami tomcat 9.0.45, 9.0.122, 10.1.60, 11.0.26
  • apache tomcat-websocket 9.0.122, 10.1.60, 11.0.26
  • org.apache.tomcat tomcat-websocket 9.0.122, 10.1.60, 11.0.26
  • apache tomcat 9.0.122, 10.1.60, 11.0.26
  • org.apache.tomcat tomcat 9.0.122, 10.1.60, 11.0.26
  • apache tomcat-embed-websocket 9.0.122, 10.1.60, 11.0.26
  • org.apache.tomcat.embed tomcat-embed-websocket 9.0.122, 10.1.60, 11.0.26
  • tomcat9 Debian 14, Debian 13, Debian 12 9.0.70-2
  • tomcat10 Debian 14 10.1.60-1

debian advisories DEBIAN-CVE-2026-77791

  • tomcat10 hummingbird 1 10.1.60-0.1.hum1
  • tomcat10-lib hummingbird 1 10.1.60-0.1.hum1
  • tomcat10-common hummingbird 1 10.1.60-0.1.hum1
  • tomcat10-webapps hummingbird 1 10.1.60-0.1.hum1
  • tomcat10-el-5.0-api hummingbird 1 10.1.60-0.1.hum1
  • tomcat10-docs-webapp hummingbird 1 10.1.60-0.1.hum1
  • tomcat10-jsp-3.1-api hummingbird 1 10.1.60-0.1.hum1
  • tomcat10-admin-webapps hummingbird 1 10.1.60-0.1.hum1

red hat advisories RHSA-2026:68257RHSA-2026:68258

  • tomcat10 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES 15 SP6-LTSS +4 more 10.1.60-150200.5.82.2
  • tomcat SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 9.0.122-150200.123.2
  • libtcnative-1-0 SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 1.3.9-150200.6.11.2
  • tomcat11 SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Web and Scripting 15 SP7 11.0.26-150600.13.36.2
  • libtcnative-1-0 SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Web and Scripting 15 SP7 +1 more 1.3.9-150600.16.9.2
  • tomcat11 SLES for SAP applications 16.0, SLES 16.0 11.0.26-160000.1.1
  • tomcat SLES for SAP applications 16.0, SLES 16.0 9.0.122-160000.1.1
  • tomcat10 SLES for SAP applications 16.0, SLES 16.0 10.1.60-160000.1.1

suse advisories SUSE-SU-2026:4927-1SUSE-SU-2026:4546-1SUSE-SU-2026:4544-1SUSE-SU-2026:23985-1

  • tomcat11 openSUSE Leap 16.0 11.0.26-160000.1.1
  • tomcat openSUSE Leap 16.0 9.0.122-160000.1.1
  • tomcat10 openSUSE Leap 16.0 10.1.60-160000.1.1
  • libtcnative-1-0 openSUSE Leap 16.0 1.3.9-160000.1.1
  • libtcnative-2-0 openSUSE Leap 16.0 2.0.16-160000.1.1
  • tomcat openSUSE Tumbleweed 9.0.122-1.1
  • tomcat10 openSUSE Tumbleweed 10.1.60-1.1
  • tomcat11 openSUSE Tumbleweed 11.0.26-1.1

opensuse advisories openSUSE-SU-2026:21984-1openSUSE-SU-2026:11906-1openSUSE-SU-2026:11907-1openSUSE-SU-2026:11908-1

Is CVE-2026-77791 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2026-77791 updated cvss 7.5

tomcat: Apache Tomcat: Denial of Service via busy wait during WebSocket close

  • Red Hat Enterprise Linux 8 tomcat, tomcat-lib, tomcat-webapps, tomcat-el-3.0-api, tomcat-docs-webapp, tomcat-jsp-2.3-api, +2 more Red Hat Enterprise Linux 9 tomcat, tomcat-lib, tomcat-webapps, tomcat-el-3.0-api, tomcat-docs-webapp, tomcat-jsp-2.3-api, +2 more Red Hat Enterprise Linux 10 tomcat, tomcat9
    affected: workaround, no fix available
  • Red Hat JBoss Web Server 5 jws5-tomcat, jws5-tomcat-lib, jws5-tomcat-jsvc, jws5-tomcat-javadoc, jws5-tomcat-selinux, jws5-tomcat-webapps, +7 more
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Hardened Images tomcat10 10.1.60-0.1.hum1, tomcat11 11.0.26-0.1.hum1, tomcat10-lib 10.1.60-0.1.hum1, tomcat11-lib 11.0.26-0.1.hum1, tomcat10-common 10.1.60-0.1.hum1, tomcat11-common 11.0.26-0.1.hum1, +14 more
    fixed: vendor fix RHSA-2026:68257
  • Red Hat JBoss Web Server 6.2 on RHEL 8 jws6-tomcat-native 1.3.6-2.redhat_2.el8jws, jws6-tomcat 10.1.49-18.redhat_00018.1.el8jws, jws6-tomcat-lib 10.1.49-18.redhat_00018.1.el8jws, jws6-mod_cluster 2.0.5-1.Final_redhat_00001.1.el8jws, jws6-tomcat-javadoc 10.1.49-18.redhat_00018.1.el8jws, jws6-tomcat-selinux 10.1.49-18.redhat_00018.1.el8jws, +7 more Red Hat JBoss Web Server 6.2 on RHEL 9 jws6-tomcat-native 1.3.6-2.redhat_2.el9jws, jws6-tomcat 10.1.49-18.redhat_00018.1.el9jws, jws6-tomcat-lib 10.1.49-18.redhat_00018.1.el9jws, jws6-mod_cluster 2.0.5-1.Final_redhat_00001.1.el9jws, jws6-tomcat-javadoc 10.1.49-18.redhat_00018.1.el9jws, jws6-tomcat-selinux 10.1.49-18.redhat_00018.1.el9jws, +7 more Red Hat JBoss Web Server 6.2 on RHEL 10 jws6-tomcat-native 1.3.6-2.redhat_2.el10jws, jws6-tomcat 10.1.49-18.redhat_00018.1.el10jws, jws6-tomcat-lib 10.1.49-18.redhat_00018.1.el10jws, jws6-mod_cluster 2.0.5-1.Final_redhat_00001.1.el10jws, jws6-tomcat-javadoc 10.1.49-18.redhat_00018.1.el10jws, jws6-tomcat-selinux 10.1.49-18.redhat_00018.1.el10jws, +7 more
    fixed: vendor fix RHSA-2026:96228
  • Red Hat JBoss Web Server 6.2.6
    fixed: vendor fix RHSA-2026:96229
  • Red Hat JBoss Web Server 7.0 on RHEL 8 jws7-tomcat-native 1.3.7-4.redhat_4.el8jws, jws7-tomcat 11.0.21-10.redhat_00010.1.el8jws, jws7-tomcat-lib 11.0.21-10.redhat_00010.1.el8jws, jws7-mod_cluster 2.1.1-1.Final_redhat_00001.1.el8jws, jws7-tomcat-javadoc 11.0.21-10.redhat_00010.1.el8jws, jws7-tomcat-selinux 11.0.21-10.redhat_00010.1.el8jws, +7 more Red Hat JBoss Web Server 7.0 on RHEL 9 jws7-tomcat-native 1.3.7-4.redhat_4.el9jws, jws7-tomcat 11.0.21-10.redhat_00010.1.el9jws, jws7-tomcat-lib 11.0.21-10.redhat_00010.1.el9jws, jws7-mod_cluster 2.1.1-1.Final_redhat_00001.1.el9jws, jws7-tomcat-javadoc 11.0.21-10.redhat_00010.1.el9jws, jws7-tomcat-selinux 11.0.21-10.redhat_00010.1.el9jws, +7 more Red Hat JBoss Web Server 7.0 on RHEL 10 jws7-tomcat-native 1.3.7-4.redhat_4.el10jws, jws7-tomcat 11.0.21-10.redhat_00010.1.el10jws, jws7-tomcat-lib 11.0.21-10.redhat_00010.1.el10jws, jws7-mod_cluster 2.1.1-1.Final_redhat_00001.1.el10jws, jws7-tomcat-javadoc 11.0.21-10.redhat_00010.1.el10jws, jws7-tomcat-selinux 11.0.21-10.redhat_00010.1.el10jws, +7 more
    fixed: vendor fix RHSA-2026:93618
  • Red Hat JBoss Web Server 7.0.3
    fixed: vendor fix RHSA-2026:93622
  • Red Hat Enterprise Linux 6 tomcat6, tomcat6-lib, tomcat6-log4j, tomcat6-javadoc, tomcat6-webapps, tomcat6-el-2.1-api, +4 more Red Hat Enterprise Linux 7 tomcat, tomcat-lib, tomcat-jsvc, tomcat-javadoc, tomcat-webapps, tomcat-el-2.2-api, +4 more Red Hat Enterprise Linux 8 pki-servlet-engine, pki-servlet-4.0-api Red Hat Enterprise Linux 9 pki-servlet-engine, pki-servlet-4.0-api
    not affected: vulnerable code not present
show 1 more
  • Red Hat Hardened Images hi/tomcat
    not affected: component 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
last mo.

Exploit prediction

0.68% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

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

Affected packages

ecosystem package affected fixed in
bitnami tomcat
>=8.5.88, <9.0.45
>=9.0.74, <9.0.122
>=10.1.8, <10.1.60
>=11.0.0, <11.0.26
9.0.45
9.0.122
10.1.60
11.0.26

Affected products

  • Apache Software Foundation Apache Tomcat

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.