CVE-2004-0989 in libxml2
Summary
by MITRE
Multiple buffer overflows in libXML 2.6.12 and 2.6.13 (libxml2), and possibly other versions, may allow remote attackers to execute arbitrary code via (1) a long FTP URL that is not properly handled by the xmlNanoFTPScanURL function, (2) a long proxy URL containing FTP data that is not properly handled by the xmlNanoFTPScanProxy function, and other overflows related to manipulation of DNS length values, including (3) xmlNanoFTPConnect, (4) xmlNanoHTTPConnectHost, and (5) xmlNanoHTTPConnectHost.
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Analysis
by VulDB Data Team • 12/24/2024
The vulnerability described in CVE-2004-0989 represents a critical security flaw affecting libxml2 version 2.6.12 and 2.6.13, with potential impacts extending to other versions in the affected series. This issue stems from multiple buffer overflow conditions within the library's network handling functions, specifically targeting components responsible for processing FTP and HTTP URLs. The flaw exists in the fundamental network protocol handling mechanisms that applications rely upon when establishing connections to remote resources, making it particularly dangerous as it can be exploited through common web and file transfer operations.
The technical implementation of this vulnerability manifests through several distinct functions within the libxml2 library that process network connection parameters. The xmlNanoFTPScanURL function fails to properly validate the length of FTP URLs, allowing attackers to craft maliciously long URLs that exceed buffer boundaries when processed. Similarly, the xmlNanoFTPScanProxy function exhibits the same weakness when handling proxy URLs containing FTP data. Additional overflow conditions occur in xmlNanoFTPConnect and xmlNanoHTTPConnectHost functions, where DNS length values are manipulated without proper boundary checking. These buffer overflows occur because the library does not enforce strict limits on input string lengths before copying them into fixed-size memory buffers, creating opportunities for attackers to overwrite adjacent memory regions with malicious data.
The operational impact of CVE-2004-0989 extends far beyond simple denial of service scenarios, as these buffer overflows can be leveraged to execute arbitrary code on vulnerable systems. When an application using libxml2 processes a maliciously crafted URL, the buffer overflow can be exploited to overwrite return addresses, function pointers, or other critical memory structures, potentially allowing remote code execution. This vulnerability affects a wide range of applications that depend on libxml2 for XML processing, including web servers, email clients, and various network applications that handle XML data with embedded URLs. The attack vector is particularly concerning because it requires minimal privileges and can be triggered through normal network operations, making it suitable for automated exploitation across vulnerable systems.
Security practitioners should note that this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of unsafe string handling in network protocol implementations. The ATT&CK framework categorizes this as a remote code execution technique that leverages software vulnerabilities in network libraries. Mitigation strategies should focus on immediate patching of affected libxml2 versions to 2.6.14 or later, where these buffer overflow conditions have been addressed through proper input validation and boundary checking. Additionally, organizations should implement network monitoring to detect unusual URL patterns that might indicate exploitation attempts, and consider deploying application-level firewalls or web application firewalls that can filter malformed URLs before they reach vulnerable applications. The vulnerability demonstrates the critical importance of input validation in network protocol libraries and serves as a reminder that even widely used foundational components can contain dangerous security flaws that affect entire ecosystems of dependent applications.