A newly discovered flaw in libxml2, a widely-used XML parsing library, could allow attackers to compromise systems and steal sensitive data.
libxml2 is a robust XML parsing library written in C. Its versatility is enhanced by bindings for various programming languages, including C++, Python, and Ruby, making it a staple in many development environments. Applications across web services, data processing, and even system configurations leverage libxml2 for its efficient and reliable parsing capabilities.
The vulnerability, tracked as CVE-2024-40896 (CVSS 9.1) and assigned a critical severity score of 9.1, affects libxml2 versions 2.11 prior to 2.11.9, 2.12 prior to 2.12.9, and 2.13 prior to 2.13.3. The flaw resides in the library’s SAX parser, which can inadvertently expose external entities, even when developers attempt to override them. This oversight allows attackers to launch classic XML External Entity (XXE) attacks.
What is an XXE attack?
XXE attacks exploit vulnerabilities in XML processors to access local files, execute commands, and even launch denial-of-service attacks. In this case, attackers can exploit the libxml2 vulnerability to gain access to sensitive information like system files (e.g., /etc/passwd) and potentially user credentials.
The Severity of the Flaw
This vulnerability is particularly concerning because:
- It bypasses intended protection: The flaw stems from a broken protection mechanism within libxml2, making it difficult for developers to identify and mitigate the issue in their applications.
- It can lead to severe consequences: Beyond data theft, successful exploitation could lead to Remote Code Execution (RCE) in misconfigured environments, giving attackers complete control over the system. Furthermore, attackers could trigger Denial of Service (DoS) by exhausting system resources.
What should you do?
Users and developers are urged to update to the latest versions of libxml2 (2.11.9, 2.12.9, or 2.13.3) immediately. System administrators should also scan their systems for potentially vulnerable applications that rely on libxml2.
