CVE-2023-40167

Workarounds

There is no workaround as there is no known exploit scenario.

Original Report

RFC 9110 Secion 8.6 defined the value of Content-Length header should be a string of 0-9 digits. However we found that Jetty accepts "+" prefixed Content-Length, which could lead to potential HTTP request smuggling.

Payload:

 POST / HTTP/1.1
 Host: a.com
 Content-Length: +16
 Connection: close
 ​
 0123456789abcdef

When sending this payload to Jetty, it can successfully parse and identify the length.

When sending this payload to NGINX, Apache HTTPd or other HTTP servers/parsers, they will return 400 bad request.

This behavior can lead to HTTP request smuggling and can be leveraged to bypass WAF or IDS.

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.

CVE-2023-40167 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (9.4.52, 10.0.16, 11.0.16, 12.0.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2023-40167? CVE-2023-40167 is a medium-severity security vulnerability in org.eclipse.jetty:jetty-http (maven), affecting versions >= 9.0.0, <= 9.4.51. It is fixed in 9.4.52, 10.0.16, 11.0.16, 12.0.1.
2. How severe is CVE-2023-40167? CVE-2023-40167 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of org.eclipse.jetty:jetty-http are affected by CVE-2023-40167? org.eclipse.jetty:jetty-http (maven) versions >= 9.0.0, <= 9.4.51 is affected.
4. Is there a fix for CVE-2023-40167? Yes. CVE-2023-40167 is fixed in 9.4.52, 10.0.16, 11.0.16, 12.0.1. Upgrade to this version or later.
5. Is CVE-2023-40167 exploitable, and should I be worried? Whether CVE-2023-40167 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-40167 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-40167?
   • Upgrade org.eclipse.jetty:jetty-http to 9.4.52 or later
   • Upgrade org.eclipse.jetty:jetty-http to 10.0.16 or later
   • Upgrade org.eclipse.jetty:jetty-http to 11.0.16 or later
   • Upgrade org.eclipse.jetty:jetty-http to 12.0.1 or later