---
id: CVE-2026-77791
title: >-
  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 9.0.7…
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 9.0.7…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
  - CWE-1050
vendor: Apache Software Foundation
product: Apache Tomcat
affected:
  - apache_tomcat >= 11.0.0-M5 <= 11.0.25
  - apache_tomcat >= 10.1.8 <= 10.1.59
  - apache_tomcat >= 9.0.74 <= 9.0.121
  - apache_tomcat >= 8.5.88 <= 8.5.100
published: '2026-09-23'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T19:19:19.043'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77791'
references:
  - url: 'https://lists.apache.org/thread/mb1pjjooqytrl6hbvbt3rw1lqwlon4cz'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/23/24'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-77791.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-77791'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2539396'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-77791'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77791'
  - url: 'https://access.redhat.com/errata/RHSA-2026:68257'
  - url: 'https://access.redhat.com/errata/RHSA-2026:68258'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-23T12:44:33.453302Z'
ingestedAt: '2026-09-23T12:24:04.182Z'
epss: 0.00679
epssPercentile: 0.52163
patched:
  - hardened_images
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **RHSA-2026:68257** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:68257)
- **RHSA-2026:68258** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:68258)
- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat JBoss Web Server 5, Red Hat JBoss Web Server 6, Red Hat JBoss Web Server 7 · no fix planned: Red Hat JBoss Web Server 5, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-10-01 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-77791.json)