CVE-2025-1240 in WinZip
Summary
by MITRE • 02/12/2025
WinZip 7Z File Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of WinZip. 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 7Z 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-24986.
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Analysis
by VulDB Data Team • 05/06/2026
This vulnerability represents a critical out-of-bounds write condition within WinZip's 7Z file parsing functionality that enables remote code execution under specific circumstances. The flaw resides in how the software processes compressed archive files, specifically targeting the decompression and extraction routines used for 7Z format files. When processing malformed or specially crafted 7Z archives, the application fails to properly validate input data boundaries, leading to memory corruption that can be exploited by malicious actors. The vulnerability requires user interaction to be successfully exploited, meaning that targets must either visit a malicious webpage or open a specifically crafted 7Z file to trigger the vulnerable code path. This requirement for user interaction aligns with common exploit patterns for desktop applications where social engineering remains a primary attack vector.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the 7Z parsing component of WinZip. When the application encounters a 7Z file, it performs decompression operations that involve allocating memory buffers for extracted data. However, the validation logic fails to properly check array bounds or buffer limits during the decompression process, allowing an attacker to craft a malicious 7Z file that causes the application to write data beyond the allocated memory boundaries. This type of vulnerability maps directly to CWE-787: "Out-of-bounds Write" which is classified as a critical weakness in software security. The lack of proper bounds checking in memory operations creates an exploitable condition where attacker-controlled data can overwrite adjacent memory locations, potentially corrupting critical application state or executing arbitrary code.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass potential system compromise and data exposure. When successfully exploited, the vulnerability allows attackers to execute code within the context of the WinZip process, which typically runs with the privileges of the user who initiated the application. This means that if a user with administrative privileges opens a malicious 7Z file, the attacker could potentially gain elevated system access. The vulnerability affects all versions of WinZip that support 7Z file format processing, making it particularly concerning for enterprise environments where multiple users may encounter malicious content through email attachments, web downloads, or file sharing systems. The remote nature of the attack vector means that exploitation can occur without requiring physical access to the target system, making it a significant threat to organizations with distributed workforces or those that frequently exchange compressed files.
Security mitigations for this vulnerability should focus on both immediate remediation and long-term defensive measures. The primary recommendation involves applying the vendor-provided security patches that address the buffer overflow condition in the 7Z file parsing code. Organizations should also implement defensive measures such as restricting user access to potentially malicious file types, deploying application whitelisting solutions to prevent unauthorized execution of potentially vulnerable software, and establishing robust email filtering and web content security measures. From an ATT&CK framework perspective, this vulnerability maps to techniques involving initial access through malicious files and execution through legitimate user processes, making it important for security teams to monitor for unusual file access patterns and process execution behaviors. Additionally, network segmentation and endpoint detection and response solutions should be configured to identify potential exploitation attempts through anomalous memory access patterns or process injection techniques that may be used during the exploitation phase.