Learn about CVE-2023-40225 affecting HAProxy versions, where empty Content-Length headers can cause misinterpretation of payload by servers. Find mitigation steps here.
HAProxy through various versions forwards empty Content-Length headers, violating RFC 9110 section 8.6.
Understanding CVE-2023-40225
HAProxy versions through 2.8.2 may allow an HTTP/1 server behind it to interpret the payload as an extra request due to the forwarding of empty Content-Length headers.
What is CVE-2023-40225?
CVE-2023-40225 relates to a vulnerability in HAProxy versions that can lead to misinterpretation of payload by servers.
The Impact of CVE-2023-40225
In uncommon cases, this vulnerability could result in an HTTP/1 server seeing the payload as an additional request, potentially leading to miscommunication or unexpected behavior.
Technical Details of CVE-2023-40225
This section outlines the vulnerability's description, affected systems and versions, and its exploitation mechanism.
Vulnerability Description
HAProxy versions through 2.8.2 forward empty Content-Length headers, which can be misinterpreted by certain servers behind HAProxy as extra requests.
Affected Systems and Versions
The vulnerability affects multiple versions of HAProxy, including 2.0.32, 2.1.x through 2.2.30, 2.3.x through 2.4.23, 2.5.x through 2.6.15, 2.7.x through 2.7.10, and 2.8.x before 2.8.2.
Exploitation Mechanism
By sending requests with empty Content-Length headers, an attacker can potentially trigger the misinterpretation of payload by servers behind HAProxy.
Mitigation and Prevention
Protecting systems from CVE-2023-40225 involves taking immediate steps and implementing long-term security practices.
Immediate Steps to Take
Update HAProxy to versions that have addressed the vulnerability and monitor for any unusual server behavior.
Long-Term Security Practices
Regularly check for updates and patches for HAProxy, maintain strict HTTP header compliance, and conduct security audits to identify and address vulnerabilities.
Patching and Updates
Apply the latest patches provided by HAProxy to ensure that the Content-Length header forwarding behavior is corrected.