Apache Traffic Server up to 8.1.11/9.2.15/10.1.4/10.2.0 improper synchronization

Summaryinfo

A vulnerability marked as critical has been reported in Apache Traffic Server up to 8.1.11/9.2.15/10.1.4/10.2.0. This issue affects some unknown processing. The manipulation leads to improper synchronization. This vulnerability is uniquely identified as CVE-2026-111816. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Apache Traffic Server up to 8.1.11/9.2.15/10.1.4/10.2.0 and classified as critical. This issue affects an unknown code. The manipulation with an unknown input leads to a improper synchronization vulnerability. Using CWE to declare the problem leads to CWE-662. The product utilizes multiple threads or processes to allow temporary access to a shared resource that can only be exclusive to one process at a time, but it does not properly synchronize these actions, which might cause simultaneous accesses of this resource by multiple threads or processes. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Apache Traffic Server forwarded a malformed 302 response that should have been rejected as a parse error, because the Transfer-Encoding: chunked carve-out bypassed the rejection path. A response that two peers can read differently is then stored and served, allowing cache poisoning and response-framing desync. 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.

It is possible to read the advisory at lists.apache.org. The identification of this vulnerability is CVE-2026-111816 since 10/16/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/21/2026).

Upgrading to version 9.2.16, 10.1.5 or 10.2.1 eliminates this vulnerability.

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Productinfo

Vendor

• Apache

Name

• Traffic Server

Version

• 8.1.0
• 8.1.1
• 8.1.2
• 8.1.3
• 8.1.4
• 8.1.5
• 8.1.6
• 8.1.7
• 8.1.8
• 8.1.9
• 8.1.10
• 8.1.11
• 9.2.0
• 9.2.1
• 9.2.2
• 9.2.3
• 9.2.4
• 9.2.5
• 9.2.6
• 9.2.7
• 9.2.8
• 9.2.9
• 9.2.10
• 9.2.11
• 9.2.12
• 9.2.13
• 9.2.14
• 9.2.15
• 10.0
• 10.1
• 10.1.0
• 10.1.1
• 10.1.2
• 10.1.3
• 10.1.4
• 10.2.0

License

• open-source

Website

• Vendor: https://www.apache.org/

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