CVE-2006-5821 in MetaFrame
Summary
by MITRE
Heap-based buffer overflow in the IMA_SECURE_DecryptData1 function in ImaSystem.dll for Citrix MetaFrame XP 1.0 and 2.0, and Presentation Server 3.0 and 4.0, allows remote attackers to execute arbitrary code via requests to the Independent Management Architecture (IMA) service (ImaSrv.exe) with invalid size values that trigger the overflow during decryption.
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Analysis
by VulDB Data Team • 04/27/2026
The vulnerability described in CVE-2006-5821 represents a critical heap-based buffer overflow affecting Citrix MetaFrame XP and Presentation Server products. This flaw exists within the IMA_SECURE_DecryptData1 function located in the ImaSystem.dll component, which forms part of Citrix's Independent Management Architecture framework. The IMA service process Imasrv.exe listens for remote management requests and handles decryption operations for system communications, making it a prime target for remote exploitation. The vulnerability specifically manifests when the service processes requests containing malformed size parameters during the decryption phase, leading to unauthorized memory manipulation through heap corruption.
The technical exploitation of this vulnerability follows a classic heap overflow pattern where insufficient input validation allows attackers to write beyond allocated memory boundaries. When the IMA_SECURE_DecryptData1 function receives invalid size values, it fails to properly validate these parameters before using them in memory allocation and copying operations. This validation failure creates a condition where an attacker can manipulate the decryption process to overwrite adjacent heap memory regions, potentially corrupting critical data structures or executable code pointers. The heap-based nature of the vulnerability means that the overflow can affect the memory management structures of the process, leading to unpredictable behavior and potential code execution.
From an operational perspective, this vulnerability presents a severe risk to Citrix server environments as it enables remote code execution without requiring authentication. Attackers can exploit this weakness by sending specially crafted requests to the IMA service port, typically port 2598 for IMA communications. The impact extends beyond simple privilege escalation as successful exploitation can lead to complete system compromise, allowing attackers to install malware, modify system configurations, or establish persistent backdoors. Organizations running affected Citrix versions face significant exposure since the vulnerability affects core management services that are often accessible from external networks, particularly in enterprise environments where Citrix servers handle critical business applications.
The vulnerability aligns with CWE-121 heap-based buffer overflow classification and maps to ATT&CK technique T1059.007 for remote code execution through service manipulation. Organizations should prioritize immediate patching of affected systems, as Citrix released security updates addressing this specific vulnerability. Network segmentation and firewall rules should be implemented to restrict access to IMA service ports, while monitoring should be enabled to detect anomalous requests to the Imasrv.exe process. The remediation approach should include comprehensive vulnerability scanning to identify all affected Citrix installations, followed by coordinated patch deployment and security hardening of management services. Additionally, implementing intrusion detection systems to monitor for exploitation attempts and conducting regular security assessments of Citrix environments will help mitigate the risk of successful exploitation attempts.