---
id: CVE-2026-87022
title: >-
  Improper handling of length parameter inconsistency vulnerability in Apache
  Tomcat allows WebSocket message smuggling when per-message-deflate is used.




  This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from
  10.1.0-M1 t…
summary: >-
  Improper handling of length parameter inconsistency vulnerability in Apache
  Tomcat allows WebSocket message smuggling when per-message-deflate is used.




  This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from
  10.1.0-M1 t…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'
cwe:
  - CWE-130
vendor: Apache Software Foundation
product: Apache Tomcat
affected:
  - apache_tomcat >= 11.0.0-M1 <= 11.0.25
  - apache_tomcat >= 10.1.0-M1 <= 10.1.59
  - apache_tomcat >= 9.0.0.M1 <= 9.0.121
  - apache_tomcat >= 8.5.0 <= 8.5.100
  - apache_tomcat >= 7.0.56 <= 7.0.109
published: '2026-09-23'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T19:19:42.183'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-87022'
references:
  - url: 'https://lists.apache.org/thread/ypvlkjqsq0480fnk9jm6h9qllddwlw4w'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/23/30'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-23T14:27:17.688403Z'
ingestedAt: '2026-09-23T12:24:04.187Z'
epss: 0.00422
epssPercentile: 0.33887
---

## Overview

Improper handling of length parameter inconsistency vulnerability in Apache Tomcat allows WebSocket message smuggling when per-message-deflate is used.



This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.0.M1 through 9.0.121.



The following versions were EOS at the time the CVE was created but are known to be affected: from 8.5.0 through 8.5.100, from 7.0.56 through 7.0.109. Other unsupported versions may also be affected.



Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.1.22, which fix the issue.

## Remediation

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