Request Body Size Limit Bypass in Hono Web Application Framework

CVE-2025-59139

What is CVE-2025-59139?

A vulnerability in the Hono Web Application Framework allows attackers to bypass the configured request body size limit due to a conflicting prioritization of HTTP headers. Specifically, the flaw in the bodyLimit middleware fails to correctly disregard the Content-Length header when a Transfer-Encoding: chunked header is present. This misconfiguration can enable oversized request bodies to go unchecked, potentially leading to Denial of Service (DoS) through excessive memory or CPU consumption. The Hono team has released version 4.9.7 to address this issue and ensure compliance with HTTP standards, allowing Transfer-Encoding to take precedence over Content-Length. All users are strongly advised to update to the latest version.

References