CVE-2016-7804 in 7-zip
Summary
by MITRE
Untrusted search path vulnerability in 7 Zip for Windows 16.02 and earlier allows remote attackers to gain privileges via a Trojan horse DLL in an unspecified directory.
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Analysis
by VulDB Data Team • 05/04/2026
The vulnerability identified as CVE-2016-7804 represents a critical untrusted search path issue within 7-Zip for Windows versions 16.02 and earlier. This flaw stems from the application's improper handling of dynamic library loading mechanisms, specifically when processing compressed archives containing malicious DLL files. The vulnerability manifests when 7-Zip attempts to load required libraries during archive extraction processes, creating an exploitable condition where attacker-controlled DLLs can be loaded before legitimate system libraries. This behavior directly violates security principles of least privilege and proper library resolution, allowing malicious code execution with the privileges of the user running 7-Zip.
The technical implementation of this vulnerability aligns with CWE-427, which describes uncontrolled search path dependencies in software applications. Attackers can exploit this by placing a malicious DLL file in a directory that appears earlier in the system's search path than the legitimate 7-Zip libraries. When a user opens a specially crafted archive containing the malicious DLL, the system's dynamic linker resolves the library load request to the attacker-controlled file rather than the intended legitimate component. This process occurs during normal archive operations, making the attack vector particularly insidious as it requires no special privileges or complex exploitation techniques beyond crafting the malicious archive.
The operational impact of CVE-2016-7804 extends beyond simple privilege escalation to encompass full system compromise potential. Since 7-Zip is commonly used for decompressing various archive formats including zip, rar, and 7z files, attackers can leverage this vulnerability through various attack vectors such as phishing emails, malicious websites, or compromised software distribution channels. The vulnerability affects both local and remote attack scenarios, as malicious actors can deliver exploit payloads through compromised archives that users might legitimately download or receive. This creates a significant risk for enterprise environments where users frequently interact with external archives and may inadvertently execute malicious code that elevates their privileges to system level. The attack requires minimal user interaction beyond opening the malicious archive, making it particularly dangerous in environments with less security awareness.
Mitigation strategies for CVE-2016-7804 should focus on immediate patching of affected 7-Zip versions to 16.03 or later, which addressed the untrusted search path issue through proper library loading mechanisms. Organizations should implement strict security policies that prevent users from opening archives from untrusted sources, particularly those received via email or downloaded from unknown websites. The implementation of application whitelisting solutions can help prevent execution of unauthorized DLL files, while system hardening measures should include configuring the Windows search path to prioritize system directories over user directories. Additionally, security awareness training should emphasize the risks of opening archives from unknown sources, and network-level controls such as email filtering and web proxies should be configured to scan and block suspicious archive files. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and execution through legitimate system tools, making it a significant concern for organizations seeking to maintain secure computing environments.