A security flaw in Foxit PDF Reader has been discovered that could enable local attackers to escalate their privileges to the highest system level. The Foxit PDF Reader vulnerability, identified as CVE-2026-57239, impacts installations running versions prior to 2026.2 and stems from improper security controls in the application’s update mechanism.
How Does the Privilege Escalation Attack Work?
The vulnerability allows an attacker who already has code execution capabilities on a target system to elevate their access to NT AUTHORITY\SYSTEM, the most privileged account level in Windows environments. This escalation is made possible through a DLL sideloading technique that exploits weaknesses in how Foxit PDF Reader handles its updater workflow.
According to the disclosure, the security issue arises from the insecure handling of an updater process that can be triggered by a user-writable file. This design flaw creates an opportunity for attackers to inject malicious dynamic-link library (DLL) files into the update process, which the application then loads with elevated privileges.
Which Versions Are Affected?
The vulnerability affects all Foxit PDF Reader installations running versions earlier than 2026.2. Organizations and individual users who have not updated to version 2026.2 or later remain exposed to potential exploitation through this privilege escalation vector.
What Are the Security Implications?
While this vulnerability requires an attacker to already have local access and code execution capabilities on a target system, the ability to escalate to SYSTEM-level privileges represents a significant security concern. Once an attacker achieves NT AUTHORITY\SYSTEM access, they gain complete control over the compromised machine, including the ability to install software, modify system files, create new accounts with full privileges, and access sensitive data without restriction.
The DLL sideloading technique exploited in this case is particularly concerning because it leverages legitimate application functionality to execute malicious code, making detection more challenging for security tools that rely on behavioral analysis.
Should Users Take Immediate Action?
Users and organizations running affected versions of Foxit PDF Reader should prioritize updating to version 2026.2 or later to remediate this security issue. While the vulnerability requires local access to exploit, it could be chained with other attack vectors to achieve more sophisticated compromise scenarios, particularly in enterprise environments where initial access may be obtained through phishing or other social engineering techniques.
Source: GBHackers Security