CVE-2024-27303 in app-builder-lib
Summary
by MITRE • 03/06/2024
electron-builder is a solution to package and build a ready for distribution Electron, Proton Native app for macOS, Windows and Linux. A vulnerability that only affects eletron-builder prior to 24.13.2 in Windows, the NSIS installer makes a system call to open cmd.exe via NSExec in the `.nsh` installer script. NSExec by default searches the current directory of where the installer is located before searching `PATH`. This means that if an attacker can place a malicious executable file named cmd.exe in the same folder as the installer, the installer will run the malicious file. Version 24.13.2 fixes this issue. No known workaround exists. The code executes at the installer-level before the app is present on the system, so there's no way to check if it exists in a current installer.
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Analysis
by VulDB Data Team • 12/03/2025
The vulnerability identified as CVE-2024-27303 affects electron-builder versions prior to 24.13.2 and specifically impacts Windows installer builds created using the NSIS installer framework. This issue represents a critical path traversal and privilege escalation vulnerability that exploits the insecure execution of system commands within the installer process. The vulnerability exists in the NSIS installer script where the system call to open cmd.exe is executed through the NSExec command without proper path validation or sanitization. The NSExec command, by default, follows a specific search order that prioritizes the current directory over the system PATH environment variable, creating a dangerous execution context where local files can masquerade as system binaries.
The technical flaw stems from the improper handling of executable paths within the NSIS installer framework used by electron-builder. When the installer script executes NSExec to launch cmd.exe, it does not explicitly specify the full path to the system command, allowing the Windows operating system to resolve the command based on its default search order. This search order places the current working directory at a higher priority than the system PATH, meaning that if an attacker can place a malicious executable named cmd.exe in the same directory as the legitimate installer, the installer will execute the malicious binary instead of the legitimate system command. This vulnerability falls under CWE-427 Uncontrolled Search Path Element, which specifically addresses the issue of programs using insecure search paths that can lead to arbitrary code execution.
The operational impact of this vulnerability is severe as it allows attackers to achieve arbitrary code execution during the installation process before any application components are present on the target system. Since the malicious code executes at the installer level, it operates with the privileges of the user running the installer, potentially enabling privilege escalation attacks or the installation of additional malicious software. The attack vector is particularly concerning because it requires minimal user interaction beyond running the installer, and the attacker only needs to place a malicious binary in the same directory as the installer. This vulnerability affects the entire Windows platform and is not limited to specific applications or versions, making it a widespread concern for any Electron or Proton Native applications distributed using affected versions of electron-builder.
Mitigation strategies for this vulnerability are limited due to the nature of the flaw occurring at the installer level rather than within the application itself. The primary and recommended solution is to upgrade to electron-builder version 24.13.2 or later, which implements proper path resolution for system commands within the NSIS installer scripts. Organizations should immediately assess their current electron-builder versions and update to the patched version to eliminate the risk. Additionally, security teams should implement strict access controls on installer distribution directories to prevent unauthorized modifications, though this approach provides only partial protection since the vulnerability can be exploited through various attack vectors including network-based delivery. The vulnerability also aligns with ATT&CK technique T1059.001 Command and Scripting Interpreter: PowerShell, as it involves the execution of system commands through potentially compromised installer components. Organizations should also consider implementing application whitelisting policies and monitoring for suspicious executable activity in installer directories to detect potential exploitation attempts. This vulnerability demonstrates the critical importance of secure coding practices in installer development and highlights the need for proper path validation even in seemingly routine system calls.