---
id: CVE-2025-55702
title: >-
  Apache Traffic Server: An unread Expect: 100-continue request body is framed
  as a new request
summary: >-
  When a client sends a POST with Expect: 100-continue and the origin answers
  before reading the body, Apache Traffic Server parses the unread body left on
  the client connection as the next request. An attacker behind a front-end
  proxy tha…
severity: high
cvss: 8.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N'
cvssSource: cna
cwe:
  - CWE-444
vendor: Apache Software Foundation
product: Apache Traffic Server
affected:
  - apache_traffic_server >= 8.0.0 <= 8.1.11
  - apache_traffic_server >= 9.0.0 <= 9.2.15
  - apache_traffic_server >= 10.0.0 <= 10.1.4
  - apache_traffic_server 10.2.0
published: '2026-10-21'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T18:24:21.377Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-55702'
references:
  - url: 'https://lists.apache.org/thread/r95dq29ywcd1f4x30snxlqmb12z4s4kc'
tags:
  - cve.org
ingestedAt: '2026-10-21T19:10:31.403Z'
---

## Overview

When a client sends a POST with Expect: 100-continue and the origin answers before reading the body, Apache Traffic Server parses the unread body left on the client connection as the next request. An attacker behind a front-end proxy that shares connections to Traffic Server can use this to smuggle requests past the front end and desynchronize responses for other users.



This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0.



Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

## Affected

- `apache_traffic_server >= 8.0.0 <= 8.1.11`
- `apache_traffic_server >= 9.0.0 <= 9.2.15`
- `apache_traffic_server >= 10.0.0 <= 10.1.4`
- `apache_traffic_server 10.2.0`

## Remediation

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