CVE-2010-20119 in Mail
Summary
by MITRE • 08/21/2025
CommuniCrypt Mail versions up to and including 1.16 contains a stack-based buffer overflow vulnerability in its ANSMTP.dll and AOSMTP.dll ActiveX controls, specifically within the AddAttachments() method. This method fails to properly validate the length of input strings, allowing data to exceed the bounds of a fixed-size stack buffer. When invoked with an overly long string, the control can corrupt adjacent memory structures, including exception handlers, leading to potential control flow disruption.
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Analysis
by VulDB Data Team • 08/21/2025
The vulnerability identified as CVE-2010-20119 represents a critical stack-based buffer overflow flaw within CommuniCrypt Mail software versions 1.16 and earlier. This issue specifically affects the ANSMTP.dll and AOSMTP.dll ActiveX controls that are integral components of the email client application. The vulnerability stems from insufficient input validation mechanisms within the AddAttachments() method, which serves as the primary entry point for exploiting this memory corruption flaw. The flaw exists at the core of how the application handles file attachment data, making it particularly dangerous as email clients are frequently used and often executed with elevated privileges on user systems.
The technical implementation of this vulnerability demonstrates a classic stack buffer overflow condition where the AddAttachments() method processes user-provided string data without adequate bounds checking. When an attacker supplies an excessively long string parameter to this method, the input data overflows the predetermined stack buffer space allocated for attachment handling. This overflow corrupts adjacent memory locations including saved instruction pointers, return addresses, and exception handling structures that are crucial for proper program execution. The memory corruption occurs due to the absence of proper string length validation and buffer size enforcement, allowing arbitrary data to overwrite critical program state information. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental memory safety issue that has been consistently identified as one of the most prevalent causes of application crashes and potential remote code execution.
The operational impact of this vulnerability extends beyond simple application instability to potentially enable sophisticated exploitation techniques that can compromise entire system environments. When the buffer overflow occurs during the execution of the AddAttachments() method, the corrupted memory structures can cause the application to crash or behave unpredictably, leading to denial of service conditions. However, more critically, the corruption of exception handlers and control flow information opens possibilities for exploitation through techniques such as return-oriented programming or direct instruction pointer manipulation. Attackers could potentially leverage this vulnerability to execute arbitrary code within the context of the CommuniCrypt Mail process, which typically runs with the privileges of the user who initiated the application. The vulnerability's potential for remote code execution makes it particularly concerning in enterprise environments where email clients are frequently used to process untrusted content from external sources. According to ATT&CK framework, this vulnerability maps to T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, as it enables an attacker to execute malicious code on a target system through a client-side application.
Mitigation strategies for CVE-2010-20119 should prioritize immediate remediation through software updates from the vendor, as the vulnerability exists in versions up to 1.16 and earlier. Organizations should implement comprehensive patch management protocols to ensure all instances of CommuniCrypt Mail are updated to versions that contain proper input validation and buffer boundary checks. Additionally, administrators should consider implementing application whitelisting policies that restrict the execution of ActiveX controls from untrusted sources, particularly in environments where email processing occurs. Network-based mitigations such as email filtering and sandboxing mechanisms can provide additional layers of protection by preventing malicious attachments from reaching end users. The vulnerability also highlights the importance of secure coding practices and input validation in ActiveX component development, emphasizing the need for thorough code reviews and security testing before deployment. System administrators should monitor for any suspicious behavior or crashes related to email client applications, as these could indicate exploitation attempts. Given that this vulnerability affects legacy software, organizations should also consider transitioning to more modern email client solutions that incorporate better memory safety mechanisms and are regularly updated with security patches.