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.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact High

Subsequent System Integrity Impact High

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Changed

Confidentiality Impact High

Integrity Impact High

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Apache Software Foundation Apache Traffic Server unaffected
Version Status Constraints
8.0.0 affected ≤ 8.1.11
9.0.0 affected ≤ 9.2.15
10.0.0 affected ≤ 10.1.4
10.2.0 affected —

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Project Subscriptions

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Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://lists.apache.org/thread/r95dq29ywcd1f4x30snxlqmb12z4s4kc cve-icon cve-icon
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'}

Projects

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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

Updated: 2026-10-21T22:00:18Z

Weaknesses