CVE-2009-3707 in Server
Summary
by MITRE
VMware Authentication Daemon 1.0 in vmware-authd.exe in the VMware Authorization Service in VMware Workstation 7.0 before 7.0.1 build 227600 and 6.5.x before 6.5.4 build 246459, VMware Player 3.0 before 3.0.1 build 227600 and 2.5.x before 2.5.4 build 246459, VMware ACE 2.6 before 2.6.1 build 227600 and 2.5.x before 2.5.4 build 246459, and VMware Server 2.x allows remote attackers to cause a denial of service (process crash) via a \x25\xFF sequence in the USER and PASS commands, related to a "format string DoS" issue. NOTE: some of these details are obtained from third party information.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 10/14/2025
The vulnerability identified as CVE-2009-3707 represents a critical format string vulnerability within the VMware Authentication Daemon component that affects multiple VMware products including Workstation, Player, ACE, and Server. This flaw exists in the vmware-authd.exe process which handles authentication requests for the VMware Authorization Service, creating a significant security risk that can be exploited by remote attackers to disrupt system operations.
The technical implementation of this vulnerability stems from improper input validation within the authentication daemon's handling of USER and PASS commands. When the daemon receives a malformed authentication request containing the specific sequence %�, it fails to properly sanitize the input before processing, leading to a format string exploitation scenario. This type of vulnerability falls under CWE-134 which specifically addresses the use of non-constant format strings, making it a direct instance of insecure coding practices that can lead to arbitrary code execution or process termination.
The operational impact of this vulnerability extends beyond simple denial of service as it creates a pathway for remote attackers to systematically crash the authentication daemon process, effectively rendering the VMware authorization service unavailable. This disruption affects the entire VMware product ecosystem by preventing legitimate authentication requests from being processed, potentially leading to complete service unavailability for users attempting to access virtual machines or manage VMware environments. The vulnerability is particularly concerning because it operates at the authentication layer where attackers can leverage it to gain control over critical system functions.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, specifically targeting service availability. The exploit requires minimal privileges and can be executed remotely, making it particularly dangerous in enterprise environments where VMware products are extensively deployed. The vulnerability demonstrates poor input validation practices that should have been addressed through proper security coding standards and input sanitization procedures.
The remediation approach for this vulnerability requires immediate patching of all affected VMware products to version 7.0.1 build 227600 or higher for Workstation 7.0, and similar updated versions for other affected products. Organizations should implement network segmentation to limit exposure of VMware services to untrusted networks, while also monitoring for potential exploitation attempts. Additionally, security teams should consider implementing intrusion detection systems capable of identifying the specific %� sequence pattern associated with this exploit, providing early warning capabilities for potential attacks.
The vulnerability serves as a critical reminder of the importance of proper input validation and format string handling in authentication systems. Given that authentication services represent prime targets for attackers seeking to compromise system availability, organizations must prioritize patch management for such critical components. This issue highlights the necessity of comprehensive security testing including fuzzing and input validation reviews to identify similar vulnerabilities in authentication and service components that could be exploited to achieve system disruption or unauthorized access.