CVE-2026-19203 is a vulnerability in Eclipse Jetty
Published on September 8, 2026
A client may issue specially crafted HTTP/1.1 chunked requests to a Jetty server that cause Jetty and an intermediary proxy to interpret different request boundaries, potentially resulting in HTTP request smuggling. This is caused by Jetty accepting a lone LF character as a terminator in parts of chunked request parsing. Depending on the Jetty version and configured HTTP compliance mode, this may occur in chunk extensions, chunk data termination, or trailer termination.
Vulnerability Analysis
CVE-2026-19203 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
What is a HTTP Request Smuggling Vulnerability?
When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.
CVE-2026-19203 has been classified to as a HTTP Request Smuggling vulnerability or weakness.
Products Associated with CVE-2026-19203
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Affected Versions
Eclipse Foundation Eclipse Jetty:- Version 12.1.0, <= 12.1.11 is affected.
- Version 12.0.0, <= 12.0.37 is affected.
- Version 11.0.0, <= 11.0.31 is affected.
- Version 10.0.0, <= 10.0.31 is affected.
- Version 9.4.0, <= 9.4.63 is affected.