CVE-2023-40167: Debian Linux

Medium severity, CVSS 5.3. EPSS: 1.3% chance of exploitation in the next 30 days.

Jetty is a Java based web server and servlet engine. Prior to versions 9.4.52, 10.0.16, 11.0.16, and 12.0.1, Jetty accepts the `+` character proceeding the content-length value in a HTTP/1 header field. This is more permissive than allowed by the RFC and other servers routinely reject such requests with 400 responses. There is no known exploit scenario, but it is conceivable that request smuggling could result if jetty is used in combination with a server that does not close the connection after sending such a 400 response. Versions 9.4.52, 10.0.16, 11.0.16, and 12.0.1 contain a patch for this issue. There is no workaround as there is no known exploit scenario.

Affected products

• Debian Debian Linux: version 10.0 only; version 11.0 only; version 12.0 only
• Eclipse Jetty: from 9.0.0, before 9.4.52 (fixed in 9.4.52); from 10.0.0, before 10.0.16 (fixed in 10.0.16); from 11.0.0, before 11.0.16 (fixed in 11.0.16); version 12.0.0 only

Published 2023-09-15. Last modified 2026-06-17.