CVE-2024-11950 in Classic
Summary
by MITRE • 12/12/2024
XnSoft XnView Classic RWZ File Parsing Integer Underflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of XnSoft XnView Classic. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the parsing of RWZ files. The issue results from the lack of proper validation of user-supplied data, which can result in an integer underflow before writing to memory. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-22913.
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Analysis
by VulDB Data Team • 05/05/2026
The CVE-2024-11950 vulnerability represents a critical remote code execution flaw in XnSoft XnView Classic software, specifically within its RWZ file parsing functionality. This vulnerability classifies under CWE-191 Integer Underflow, which occurs when a signed integer is decremented below its minimum representable value, creating unpredictable behavior in memory operations. The flaw exists in the software's handling of RWZ (XnView compressed) files, which are commonly used for image compression and storage within the XnView ecosystem. These files are typically encountered when users open image collections or browse through compressed image archives within the application.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the RWZ file parser. When processing malformed RWZ files, the application fails to properly validate integer values during the decompression process, leading to an integer underflow condition. This underflow creates a scenario where the application attempts to allocate memory or perform operations using negative integer values, which can result in memory corruption and arbitrary code execution. The vulnerability is particularly dangerous because it allows remote attackers to trigger this condition through crafted RWZ files without requiring any special privileges beyond basic user access. The integer underflow specifically manifests during the calculation of buffer sizes or memory allocation parameters, where an attacker-controlled value causes the calculation to wrap around to an unexpectedly small or negative value, potentially leading to heap corruption.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to operate within the security context of the currently running XnView process. This means that successful exploitation could result in complete system compromise, especially if the target system runs with elevated privileges. The vulnerability requires user interaction to exploit, typically through the opening of a malicious RWZ file or visiting a web page that automatically triggers the file processing. This user interaction requirement provides some mitigation but does not eliminate the threat, as social engineering attacks can easily convince users to open malicious files. The vulnerability's presence in a widely used image viewing application means that it could potentially affect numerous users across different environments, from personal computers to enterprise systems that utilize XnView for image management.
Mitigation strategies for CVE-2024-11950 should prioritize immediate software updates from XnSoft, as the vendor has likely released patches addressing this specific integer underflow condition. Organizations should implement strict file validation policies that prevent automatic execution of potentially malicious files, particularly those from untrusted sources. Network-based mitigations could include implementing content filtering solutions that block RWZ file types or restrict access to known malicious domains. The ATT&CK framework categorizes this vulnerability under T1203 Exploitation for Client Execution, as it leverages a client-side application vulnerability to execute code remotely. Security teams should also consider deploying application whitelisting controls that restrict execution of XnView Classic to trusted environments and monitor for unusual file processing activities. Additionally, users should be educated about the risks of opening unknown or untrusted files, particularly those with .rwz extensions, as this vulnerability can be exploited through various attack vectors including email attachments, web downloads, and removable media.