CVE-2007-4607: Quiksoft EasyMail SMTP ActiveX control buffer overflow

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 19 September 2026. Confidence: medium.

high priorityThe flaw allows remote code execution with no authentication and public exploit code exists, though exploitation requires the victim to load content that instantiates the control.

What it is

The EasyMailSMTPObj ActiveX control in emsmtp.dll 6.0.1, shipped with Quiksoft EasyMail SMTP Object and used by Postcast Server Pro 3.0.61 and other products, contains a stack buffer overflow reachable through a long argument to the SubmitToExpress method. Successful exploitation allows arbitrary code execution in the context of the process hosting the control, which is a serious risk for any application that instantiates it. The record notes the issue may have been fixed in version 6.0.3.15, but this is not confirmed by the supplied data.

Impact

An attacker who can invoke the vulnerable method with a crafted long argument can overwrite memory and execute arbitrary code under the privileges of the hosting application or user. This can lead to full compromise of the affected host or the user's session.

Attack surface

The flaw is reached remotely over the network through the ActiveX control's SubmitToExpress method, per the AV:N vector, but the AC:M rating indicates some conditions must be met, typically that a victim loads a page or document that instantiates the control. No authentication is required (Au:N), though user interaction with the malicious content is generally needed to trigger the control.

Exploitation

The control is not listed in CISA KEV, but EPSS is high at roughly 0.56 (99th percentile), and references include an Exploit-tagged SecurityFocus entry and an Exploit-DB entry, indicating public exploit code exists. No ransomware usage is documented.

What to do

• Upgrade EasyMail SMTP Object to version 6.0.3.15 or later if that version is confirmed to fix the issue; otherwise apply the vendor's current patched release.
• Remove or unregister emsmtp.dll on systems that do not require the EasyMail SMTP functionality.
• Set the kill bit for the EasyMailSMTPObj ActiveX control in Internet Explorer and restrict ActiveX execution in browsers and mail clients.
• Apply application allowlisting and least-privilege controls so a compromised hosting process cannot escalate.
• Block or restrict network delivery of content that instantiates the control where feasible.

Detection

• Monitor for processes loading emsmtp.dll and for crashes or memory corruption events in applications that host the control.
• Search endpoint and web proxy logs for known exploit URLs or payloads associated with the SubmitToExpress overflow.
• Alert on unexpected child processes or code execution originating from applications that instantiate EasyMailSMTPObj.
• Inventory hosts still carrying emsmtp.dll 6.0.1 or the affected Postcast Server Pro build.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.