CVE-2026-7279: AVACAST DLL Hijacking RCE Vulnerability

CVE-2026-7279 Overview

AVACAST, a multimedia casting application developed by eMPIA Technology, contains a DLL Hijacking vulnerability (CWE-427) that allows authenticated local attackers to execute arbitrary code with elevated system privileges. By placing a malicious DLL file in a specific directory, attackers can achieve code execution when the application loads the compromised library.

Critical Impact

Local authenticated attackers can achieve arbitrary code execution with SYSTEM privileges through DLL hijacking, potentially leading to complete system compromise.

Affected Products

• AVACAST by eMPIA Technology (specific versions not disclosed)

Discovery Timeline

• 2026-04-28 - CVE CVE-2026-7279 published to NVD
• 2026-04-28 - Last updated in NVD database

Technical Details for CVE-2026-7279

Vulnerability Analysis

This DLL Hijacking vulnerability exists due to improper DLL loading practices in the AVACAST application. When the application starts or performs certain operations, it attempts to load required dynamic-link libraries from directories that may be writable by local users. If the application searches for DLLs in insecure locations before secure system directories, or fails to validate the authenticity of loaded libraries, an attacker can exploit this behavior.

The vulnerability requires local authentication, meaning an attacker must already have access to the target system. However, once exploited, the code execution occurs within the context of the AVACAST process, which runs with elevated SYSTEM privileges. This privilege escalation makes the vulnerability particularly dangerous, as it allows a lower-privileged user to gain full control over the affected system.

Root Cause

The root cause of CVE-2026-7279 is the application's insecure DLL search order implementation (CWE-427: Uncontrolled Search Path Element). The AVACAST application does not properly restrict the locations from which DLL files are loaded, nor does it verify the integrity or authenticity of DLLs before loading them. This allows attackers to place malicious DLLs in directories that are searched before the legitimate system directories.

Attack Vector

The attack is executed locally by an authenticated user. The attacker identifies the target directory where AVACAST searches for DLLs and places a malicious DLL with the same name as a legitimate library. When the application launches or performs an operation requiring that library, it loads the attacker's malicious DLL instead, executing arbitrary code with the privileges of the AVACAST process.

The attack requires the attacker to have write access to the vulnerable directory path. Once the malicious DLL is in place, the exploitation occurs automatically when a privileged user or service starts the AVACAST application, making this an effective technique for privilege escalation.

For detailed technical analysis, refer to the TW-CERT Security Advisory.

Detection Methods for CVE-2026-7279

Indicators of Compromise

• Unexpected or unsigned DLL files appearing in AVACAST installation directories
• DLL files with legitimate Windows system names located outside C:\Windows\System32
• Recent file modification timestamps on DLL files in application directories
• Process execution events showing AVACAST loading DLLs from non-standard paths

Detection Strategies

• Monitor for DLL loading events from writable directories using Windows Sysmon Event ID 7
• Implement application whitelisting to detect unauthorized library loading
• Deploy endpoint detection rules to identify unsigned DLLs loaded by AVACAST processes
• Audit file creation events in AVACAST installation and working directories

Monitoring Recommendations

• Enable Windows Event Logging for process creation and DLL loading events
• Configure file integrity monitoring on AVACAST installation directories
• Set up alerts for privilege escalation attempts from AVACAST process context
• Monitor for suspicious child processes spawned by AVACAST with SYSTEM privileges

How to Mitigate CVE-2026-7279

Immediate Actions Required

• Restrict write permissions on AVACAST installation and application directories
• Audit existing DLL files in application directories for unauthorized modifications
• Apply principle of least privilege to user accounts that interact with AVACAST
• Monitor for exploitation attempts using endpoint detection capabilities

Patch Information

Consult eMPIA Technology for official patches addressing CVE-2026-7279. Additional guidance is available through the TW-CERT Security Advisory and TW-CERT Security Notification.

Workarounds

• Configure strict ACLs on all directories in the AVACAST DLL search path to prevent unauthorized writes
• Run AVACAST with reduced privileges where functionality permits
• Implement application control policies to block execution of unsigned or untrusted DLLs
• Consider deploying in an isolated environment until official patches are available