CVE-2023-38852 in libxlsv
Summary
by MITRE • 08/15/2023
Buffer Overflow vulnerability in libxlsv.1.6.2 allows a remote attacker to execute arbitrary code and cause a denial of service via a crafted XLS file to the unicode_decode_wcstombs function in xlstool.c:266.
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Analysis
by VulDB Data Team • 11/06/2025
The buffer overflow vulnerability identified as CVE-2023-38852 resides within the libxlsv library version 1.6.2, specifically targeting the unicode_decode_wcstombs function located in xlstool.c at line 266. This flaw represents a critical security weakness that can be exploited by remote attackers to execute arbitrary code or induce denial of service conditions. The vulnerability manifests when processing crafted XLS spreadsheet files that contain maliciously constructed unicode sequences designed to trigger the buffer overflow during decoding operations. The affected library serves as a component for parsing and handling Microsoft Excel spreadsheet formats, making it a potential entry point for attackers targeting systems that process or handle Excel files.
This buffer overflow vulnerability falls under the CWE-121 category of stack-based buffer overflow, where insufficient bounds checking allows an attacker to overwrite adjacent memory locations in the program's stack. The technical flaw occurs because the unicode_decode_wcstombs function fails to properly validate the length of input unicode strings before copying them into fixed-size buffers. When a maliciously crafted XLS file contains unicode sequences that exceed the allocated buffer space, the function continues to write beyond the intended memory boundaries, potentially overwriting return addresses, function pointers, or other critical program data structures. The vulnerability is particularly dangerous because it operates in a remote attack scenario, meaning an attacker can exploit it without requiring local system access, simply by enticing a victim to open a specially crafted XLS file through an application that utilizes the vulnerable libxlsv library.
The operational impact of this vulnerability extends across multiple system components and threat vectors, as it can lead to complete system compromise or service disruption. Attackers exploiting this flaw can achieve arbitrary code execution, potentially allowing them to install malware, establish backdoors, or escalate privileges within the affected system. The denial of service aspect means that even if code execution is not achieved, the vulnerability can still render applications unusable by causing crashes or system instability. This vulnerability affects any system or application that relies on libxlsv version 1.6.2 for processing Excel files, including office automation systems, data analysis platforms, and document management solutions. The attack surface is particularly broad given that Excel files are commonly used in business environments, making this vulnerability attractive to threat actors seeking to compromise enterprise networks through spearphishing campaigns or other delivery mechanisms.
Mitigation strategies for CVE-2023-38852 should prioritize immediate patching of the libxlsv library to version 1.6.3 or later, which contains the necessary fixes for the buffer overflow vulnerability. Organizations should implement comprehensive input validation measures that enforce strict bounds checking on all unicode data processing operations, particularly in functions that handle character encoding conversions. Network segmentation and application whitelisting can help reduce the attack surface by limiting which systems can process Excel files and preventing unauthorized access to vulnerable applications. Security monitoring should include detection of suspicious file access patterns and unusual memory usage that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1059.007 for command and script interpreter and T1499.004 for network denial of service, making it relevant for threat hunting and incident response activities. System administrators should also consider implementing sandboxing mechanisms for Excel file processing and deploying intrusion detection systems that can identify malicious XLS file patterns. Regular security assessments of third-party libraries and components should be conducted to identify and remediate similar vulnerabilities before they can be exploited by adversaries.