CVE-2025-6442

This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions.
The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests.

It was discovered that the REXML module bunded into Ruby incorrectly handled parsing XML documents with repeated instances of certain characters. An attacker could possibly use this issue to cause REXML to consume excessive resources, leading to a denial of service. Ubuntu 18.04 LTS and Ubuntu 20.04 LTS were previously addressed in USN-7256-1 and USN-7734-1. This update addresses the issue in Ubuntu 16.04 LTS. It was discovered that the REXML module bunded into Ruby incorrectly handled parsing XML documents with repeated instances of certain characters. An attacker could possibly use this issue to cause REXML to consume excessive resources, leading to a denial of service. Ubuntu 20.04 LTS was previously addressed in USN-7256-1. This update addresses the issue in Ubuntu 16.04 LTS and Ubuntu 18.04 LTS.