CVE-2023-31102 in 7-zip
Summary
by MITRE • 11/03/2023
Ppmd7.c in 7-Zip before 23.00 allows an integer underflow and invalid read operation via a crafted 7Z archive.
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Analysis
by VulDB Data Team • 05/12/2026
The vulnerability identified as CVE-2023-31102 affects the Ppmd7.c component within 7-Zip version 23.00 and earlier, representing a critical security flaw that can be exploited through maliciously crafted 7Z archive files. This issue specifically targets the PPMd (Prediction by Partial Matching) compression algorithm implementation, which is used for data compression and decompression within the 7-Zip archive management system. The vulnerability manifests when the software processes specially constructed archive files that manipulate the internal state management of the PPMd algorithm, creating conditions where integer underflow occurs during the decompression process.
The technical flaw stems from inadequate input validation and boundary checking within the Ppmd7.c module, where the software fails to properly validate the size parameters and state transitions during PPMd decompression operations. When processing a crafted 7Z archive, the algorithm attempts to perform arithmetic operations that result in integer underflow conditions, causing the program to access memory locations that are outside the valid range of allocated buffers. This invalid memory access pattern leads to an invalid read operation that can potentially be exploited to cause application crashes, information disclosure, or in more severe cases, arbitrary code execution depending on the specific memory layout and exploitation circumstances.
The operational impact of this vulnerability extends beyond simple application instability, as it represents a potential vector for remote code execution attacks when 7-Zip is used to process untrusted archive files. Attackers can craft malicious 7Z archives that, when opened by vulnerable 7-Zip versions, trigger the integer underflow condition and subsequent invalid memory access. This vulnerability is particularly concerning in environments where 7-Zip is used for automated archive processing or where users might encounter untrusted archive files through email attachments, file downloads, or other attack vectors. The flaw affects any system running 7-Zip versions prior to 23.00, making it a widespread concern across various operating systems and deployment scenarios where this compression utility is utilized.
Security practitioners should consider this vulnerability in the context of the CWE-190 category, which addresses integer overflow and underflow conditions, and the ATT&CK framework's technique T1059 for command and scripting interpreter and T1203 for Exploitation for Client Execution. The vulnerability demonstrates how seemingly benign archive processing functionality can become a critical attack surface when proper input validation and memory safety measures are not implemented. Organizations should immediately update to 7-Zip 23.00 or later versions to remediate this issue, while also implementing additional safeguards such as sandboxed processing of archive files, network-based filtering of archive file types, and regular security assessments of archive handling components within their systems. The vulnerability underscores the importance of maintaining up-to-date software libraries and implementing robust input validation mechanisms to prevent similar issues in compression and decompression algorithms that are widely used across enterprise and consumer environments.