---
id: CVE-2026-77756
title: >-
  Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response
  Smuggling') vulnerability in Apache Tomcat caused by processing the
  transfer-encoding header for an HTTP/1.0 request may allow an attacker to
  cause one request from ano…
summary: >-
  Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response
  Smuggling') vulnerability in Apache Tomcat caused by processing the
  transfer-encoding header for an HTTP/1.0 request may allow an attacker to
  cause one request from ano…
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-444
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 >= 9.0.47 <= 9.0.121
  - apache_tomcat >= 8.5.67 <= 8.5.100
published: '2026-09-23'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T19:19:18.720'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77756'
references:
  - url: 'https://lists.apache.org/thread/bl5b6rxqh3vb2k9bj2794vhor7o6xl3z'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/23/22'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-23T13:18:16.430403Z'
ingestedAt: '2026-09-23T11:22:32.915Z'
epss: 0.00256
epssPercentile: 0.15371
---

## Overview

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in Apache Tomcat caused by processing the transfer-encoding header for an HTTP/1.0 request may allow an attacker to cause one request from another user to fail when Tomcat is located behind a reverse proxy.



This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.47 through 9.0.121.



The following versions were EOL at the time the CVE was created but are 
known to be affected: from 8.5.67 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.