CVE-2010-2810 in Lynx
Summary
by MITRE
Heap-based buffer overflow in the convert_to_idna function in WWW/Library/Implementation/HTParse.c in Lynx 2.8.8dev.1 through 2.8.8dev.4 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a malformed URL containing a % (percent) character in the domain name.
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Analysis
by VulDB Data Team • 09/23/2021
The vulnerability identified as CVE-2010-2810 represents a critical heap-based buffer overflow within the Lynx web browser's URL parsing functionality. This flaw exists in the convert_to_idna function located in WWW/Library/Implementation/HTParse.c, affecting Lynx versions ranging from 2.8.8dev.1 through 2.8.8dev.4. The vulnerability specifically manifests when processing malformed URLs containing percent characters within domain names, creating a significant security risk for users of these affected browser versions.
The technical implementation of this vulnerability stems from inadequate input validation within the IDNA (Internationalizing Domain Names in Applications) conversion process. When the convert_to_idna function encounters a URL with a percent character in the domain portion, the heap memory allocation and subsequent string manipulation operations fail to properly bounds-check the input data. This allows attackers to overwrite adjacent heap memory regions, potentially leading to application instability or arbitrary code execution. The flaw operates at the intersection of network protocol parsing and memory management, making it particularly dangerous in web browsing contexts where users may encounter untrusted URLs.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling remote code execution. Attackers can craft malicious URLs that, when processed by the vulnerable Lynx versions, trigger the buffer overflow condition. The heap corruption can result in application crashes, forcing users to restart their browsing sessions, or more critically, allow attackers to inject and execute malicious code within the browser's memory space. This represents a significant threat to user security, particularly in environments where users may encounter untrusted web content or where the browser is used for sensitive information handling.
From a cybersecurity framework perspective, this vulnerability maps directly to CWE-121, Heap-based Buffer Overflow, and aligns with ATT&CK techniques related to code injection and privilege escalation. The vulnerability demonstrates how seemingly benign character processing can create critical security weaknesses, particularly when dealing with internationalized domain names and URL parsing. Organizations should prioritize immediate patching of affected Lynx installations and implement network monitoring to detect potential exploitation attempts. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping their browser software updated. The vulnerability underscores the critical need for robust input validation and memory safety practices in network protocol implementations, particularly in widely used open source software components.