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.
Advisories

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Fixes

Solution

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Workaround

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History

Wed, 21 Oct 2026 18:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Apache Traffic Server: An unread Expect: 100-continue request body is framed as a new request
Weaknesses CWE-444
References
Metrics cvssV3_1

{'score': 8.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N'}

cvssV4_0

{'score': 7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-10-21T18:24:21.377Z

Reserved: 2025-08-13T22:27:49.065Z

Link: CVE-2025-55702

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-21T19:16:48.120

Modified: 2026-10-21T19:16:48.120

Link: CVE-2025-55702

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses