---
id: CVE-2026-77762
title: >-
  Concurrent Execution using Shared Resource with Improper Synchronization
  ('Race Condition') vulnerability in Apache Tomcat allows an attacker to inject
  trailer fields into another HTTP/2 request.




  This issue affects Apache Tomcat: from…
summary: >-
  Concurrent Execution using Shared Resource with Improper Synchronization
  ('Race Condition') vulnerability in Apache Tomcat allows an attacker to inject
  trailer fields into another HTTP/2 request.




  This issue affects Apache Tomcat: from…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-362
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 >= 9.0.39 <= 9.0.121
  - apache_tomcat >= 8.56.59 <= 8.5.100
published: '2026-09-23'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T19:19:18.870'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77762'
references:
  - url: 'https://lists.apache.org/thread/y5r9fvjo7ol24mkoyoc0st8bqrfyqcyn'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/23/23'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-23T15:40:01.556894Z'
ingestedAt: '2026-09-23T11:22:32.915Z'
---

## Overview

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in Apache Tomcat allows an attacker to inject trailer fields into another HTTP/2 request.



This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.39 through 9.0.121.



The following versions were EOL at the time the CVE was created but are 
known to be affected: from 8.5.59 through 8.5.100. Other unsupported versions may also be affected.




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

## Remediation

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