CVE-2005-3120 in Lynx
Summary
by MITRE
Stack-based buffer overflow in the HTrjis function in Lynx 2.8.6 and earlier allows remote NNTP servers to execute arbitrary code via certain article headers containing Asian characters that cause Lynx to add extra escape (ESC) characters.
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Analysis
by VulDB Data Team • 06/29/2025
The vulnerability identified as CVE-2005-3120 represents a critical stack-based buffer overflow within the Lynx web browser's HTrjis function, affecting versions 2.8.6 and earlier. This flaw specifically manifests when processing article headers from NNTP servers that contain Asian characters, creating a condition where the application improperly handles character encoding and subsequently adds extra escape characters to the stack. The vulnerability operates through a well-defined attack vector that leverages the interaction between international character sets and the browser's internal text processing mechanisms, making it particularly dangerous in multi-lingual network environments.
The technical implementation of this vulnerability stems from inadequate input validation within the HTrjis function, which is responsible for handling text encoding transformations. When Lynx encounters article headers containing Asian characters, the function processes these characters through a series of escape sequences that are not properly bounded, leading to stack corruption. This behavior directly aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent stack memory. The flaw is particularly insidious because it requires no local privileges or user interaction beyond normal browsing activities, making it a prime target for remote exploitation.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to completely compromise the affected system. When successful, the buffer overflow allows remote code execution with the privileges of the Lynx process, potentially leading to full system compromise. The attack requires minimal prerequisites since it operates through standard NNTP protocol interactions, making it particularly dangerous for users who access newsgroups or other NNTP-based content. This vulnerability represents a significant risk for organizations that rely on Lynx for information retrieval, as it can be exploited through legitimate network traffic without detection.
Mitigation strategies for CVE-2005-3120 should prioritize immediate version upgrades to Lynx 2.8.7 or later, which contain the necessary patches to address the buffer overflow condition. System administrators should implement network segmentation to limit access to NNTP servers, particularly those known to serve content with international characters. Additionally, deploying intrusion detection systems that monitor for unusual escape character sequences in NNTP traffic can provide early warning of potential exploitation attempts. The vulnerability also highlights the importance of proper input validation and bounds checking in text processing functions, aligning with ATT&CK technique T1059.007 for command and script injection. Organizations should conduct thorough security assessments of their legacy browser installations and implement automated patch management processes to prevent similar vulnerabilities from being exploited in the future.