CVE-2025-51726: Weak Cryptographic Hash and Lacking High Entropy ASLR in CyberGhostVPNSetup.exe

Overview

The vulnerability CVE-2025-51726 presents a significant security risk to users of the CyberGhostVPNSetup.exe Windows installer. The software is exposed to potential supply-chain style attacks and privilege escalation through fake installers due to its use of the weak cryptographic hash algorithm SHA-1 and the absence of High Entropy Address Space Layout Randomization (ASLR). SHA-1 is susceptible to collision attacks, enabling malicious actors to forge SHA-1 certificates and craft fake installers that could be validated by Windows signature verification mechanisms. This issue is particularly critical on systems without strict SmartScreen or trust policy enforcement.

Vulnerability Summary

CVE ID: CVE-2025-51726
Severity: High (8.4 CVSS score)
Attack Vector: Local network
Privileges Required: None
User Interaction: Required
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

CyberGhost VPN | All versions prior to patch

How the Exploit Works

The exploit works by taking advantage of the weak SHA-1 cryptographic hash used by the CyberGhostVPNSetup.exe Windows installer. A malicious actor crafts a fake installer with a forged SHA-1 certificate, which can then be accepted by Windows signature verification mechanisms, especially on systems without strict SmartScreen or trust policy enforcement in place.
Moreover, the installer lacks High Entropy ASLR, which allows the binary to consistently load into predictable memory ranges. This predictability increases the success rate of memory corruption exploits. When these two vulnerabilities are combined, they significantly lower the bar for successful supply-chain style attacks or privilege escalation through fake installers.

Conceptual Example Code

This is a conceptual example of how the vulnerability might be exploited. The malicious actor could potentially employ a shell command to generate a forged SHA-1 certificate and attach it to a malicious installer:

# Generate SHA-1 hash for malicious installer
echo -n "malicious_installer.exe" | openssl dgst -sha1 -binary | openssl enc -base64
# Craft malicious installer with forged certificate
copy /b malicious_installer.exe+fake_certificate.exe new_installer.exe

Please note that this is a simplified and conceptual demonstration. In a real-world scenario, the process would likely involve more complex steps and tools, and the exploitation would require significant technical knowledge and resources.

Mitigation Guidance

Users are strongly advised to apply the vendor patch as soon as it becomes available. Until then, they should consider implementing a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) as a temporary mitigation measure to reduce the risk of successful exploitation.