CVE-2023-40481 in 7-zip
Summary
by MITRE • 05/03/2024
7-Zip SquashFS File Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of 7-Zip. 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 SQFS files. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-18589.
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Analysis
by VulDB Data Team • 05/12/2026
The CVE-2023-40481 vulnerability represents a critical out-of-bounds write flaw in 7-Zip's handling of SquashFS files, classified under CWE-787: "Out-of-bounds Write." This vulnerability resides in the file parsing logic that processes SquashFS container formats, which are commonly used in Linux-based systems for creating read-only file systems. The flaw specifically manifests when 7-Zip attempts to parse malformed SquashFS files, creating a scenario where user-supplied data is not properly validated before being written to memory buffers. This issue falls squarely within the ATT&CK framework under T1203: "Exploitation for Client Execution" and T1059: "Command and Scripting Interpreter," as it enables remote code execution through malicious file manipulation.
The technical implementation of this vulnerability stems from inadequate input validation within the SquashFS file parser component of 7-Zip. When processing a specially crafted SquashFS file, the application fails to verify buffer boundaries before performing memory writes, leading to a situation where data can be written beyond the allocated memory space. This memory corruption can be leveraged by attackers to overwrite adjacent memory locations, potentially including function pointers, return addresses, or other critical program data structures. The vulnerability requires user interaction to be exploited, meaning a target must either open a malicious file or visit a webpage containing such a file, making it a client-side attack vector that aligns with ATT&CK's T1204.2: "User Execution" sub-technique.
The operational impact of this vulnerability extends beyond simple remote code execution, as it can provide attackers with complete control over the affected system. An attacker who successfully exploits this vulnerability can execute arbitrary code with the privileges of the 7-Zip process, which typically runs with the permissions of the user who initiated the file operation. This could lead to privilege escalation scenarios, especially if the user has elevated privileges. The vulnerability's classification as a remote code execution flaw means that attackers do not need physical access to the system, as they can deliver malicious SquashFS files through various attack vectors including email attachments, web downloads, or compromised websites. The ZDI-CAN-18589 reference indicates this vulnerability was recognized by the Zero Day Initiative and assigned a canonical identifier for tracking and remediation purposes.
Mitigation strategies for CVE-2023-40481 should focus on both immediate patching and operational security measures. Organizations should prioritize applying the latest 7-Zip updates from the official repository, as vendors typically release patches that address the specific buffer overflow conditions. Until patches are applied, users should exercise extreme caution when handling SquashFS files from untrusted sources, implementing strict file validation procedures and sandboxing techniques. Network security controls such as email filtering and web proxies should be configured to block or quarantine suspicious SquashFS files. Additionally, system administrators should implement monitoring for unusual 7-Zip activity patterns and consider implementing application whitelisting policies that restrict execution of 7-Zip to trusted environments only. The vulnerability's nature as a buffer overflow makes it particularly susceptible to exploitation through techniques such as return-oriented programming or stack spraying, further emphasizing the need for comprehensive security measures including address space layout randomization and data execution prevention mechanisms.