Critical DoS Vulnerability in REXML Affecting Ruby Packages
Summary
UBUNTU-CVE-2024-39908: REXML is an XML toolkit for Ruby. Affects jruby versions 1.5.6-5ubuntu1 – 1.5.6-9+deb8u2build0.14.04.1~esm2. No fix is published. How to fix ↓
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Background
REXML is an XML toolkit for Ruby, widely used for parsing and manipulating XML data. It provides a simple and efficient way to handle XML documents in Ruby applications. However, recent vulnerabilities have been identified in the REXML gem, specifically versions prior to 3.3.1, which can lead to Denial of Service (DoS) attacks when processing untrusted XML inputs.
Vulnerability Detail
The vulnerability arises from the way REXML handles certain specific characters in XML documents, such as '<', '0', and '%>'. Attackers can exploit this flaw by crafting XML inputs that trigger excessive resource consumption, potentially leading to application crashes or unresponsiveness. This vulnerability is particularly concerning for applications that parse untrusted XML data, as it can be exploited without authentication or user interaction.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
If upgrading is not immediately feasible, users are advised to avoid parsing untrusted XML strings. Implement input validation to sanitize XML data before processing it with REXML.
Conclusion
The REXML vulnerability poses a significant risk to Ruby applications that process untrusted XML data. Users are strongly encouraged to upgrade to the patched version to mitigate potential attacks. For those unable to upgrade, implementing workarounds and using tools like Vulert can help manage the risk effectively.
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FAQ
REXML is a Ruby library for parsing and manipulating XML documents, providing a simple interface for developers.
Exploiting this vulnerability can lead to Denial of Service (DoS), causing applications to crash or become unresponsive when processing malicious XML.
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If an upgrade is not possible, avoid parsing untrusted XML inputs and implement input validation to mitigate the risk.
The CVSS score for this vulnerability is 4.3, indicating a medium severity level.
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