Apache Traffic Server HPACK sync bug 8.x-10.1.3
CVE-2026-65100 Published on July 29, 2026
Apache Traffic Server: HPACK encoder desynchronizes from the decoder after a failed header encode
Apache Traffic Server updates the HTTP/2 HPACK dynamic table before confirming the header block encoded successfully, so an encode failure leaves the encoder out of sync with the peer decoder and corrupts subsequent header blocks on the connection.
This issue affects Apache Traffic Server: from 8.0.0 through 8.1.9, from 9.0.0 through 9.2.14, from 10.0.0 through 10.1.3.
Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.
Vulnerability Analysis
CVE-2026-65100 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity and availability.
Weakness Type
Incorrect Behavior Order
The product performs multiple related behaviors, but the behaviors are performed in the wrong order in ways which may produce resultant weaknesses.
Products Associated with CVE-2026-65100
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Affected Versions
Apache Software Foundation Apache Traffic Server:- Version 8.0.0, <= 8.1.9 is affected.
- Version 9.0.0, <= 9.2.14 is affected.
- Version 10.0.0, <= 10.1.3 is affected.