REXML Gem Vulnerability: Untrusted XML Parsing May Cause Denial of Service

What is CVE-2024-35176?

CVE-2024-35176 is a vulnerability identified in the REXML gem, an XML parsing toolkit utilized within the Ruby programming language ecosystem. This vulnerability arises from improper handling of untrusted XML input, specifically when parsing documents containing numerous less-than symbols (<) in attribute values. If exploited, this vulnerability could potentially lead to denial of service (DoS) incidents, rendering applications utilizing REXML unresponsive, which could significantly disrupt business operations or services relying on XML processing.

Technical Details

The vulnerability affects versions of the REXML gem prior to 3.2.6. It occurs during the XML parsing process when handling untrusted XML content. Attackers can manipulate the XML input to overwhelm the parser by embedding a high concentration of < symbols within attribute values, leading to excessive resource consumption. This results in the application becoming unresponsive, creating challenges for organizations that depend on robust XML handling capabilities for their operations. To address this vulnerability, the REXML gem has released an updated version (3.2.7) that includes necessary security fixes.

Potential impact of CVE-2024-35176

1. Denial of Service: The most immediate impact of this vulnerability is the potential for denial of service. Exploitation may cause servers to become unresponsive when handling crafted XML inputs, thus disrupting the availability of services dependent on REXML for XML data processing.

2. Operational Disruption: Organizations using applications that involve XML parsing may experience operational disruptions, as affected systems could halt or slow down significantly due to resource exhaustion. This could hinder business processes that are critical for maintaining service levels.

3. Increased Vulnerability Exposure: If organizations continue to utilize outdated versions of the REXML gem, they may become attractive targets for attackers. This vulnerability highlights the risks associated with not applying timely security patches, increasing the surface area for further attacks, such as potential data breaches or unauthorized access in a broader attack chain.

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