CVE-2006-5313 in Hastymail
Summary
by MITRE
Hastymail 1.5 and earlier before 20061008 allows remote authenticated users to send arbitrary SMTP commands by placing them after a CRLF.CRLF sequence in the smtp_message parameter. NOTE: this crosses privilege boundaries if the SMTP server configuration prevents a user from establishing a direct SMTP session. NOTE: this is a different type of issue than CVE-2006-5262.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 04/24/2026
The vulnerability identified as CVE-2006-5313 affects Hastymail versions 1.5 and earlier, specifically before the 20061008 release, representing a significant security flaw in email handling mechanisms. This issue manifests as a command injection vulnerability within the SMTP message processing functionality, where authenticated users can exploit a specific sequence of characters to execute arbitrary SMTP commands on the underlying mail server. The vulnerability occurs when the smtp_message parameter contains a CRLF.CRLF sequence followed by malicious SMTP commands, allowing attackers to bypass normal email processing restrictions and potentially gain unauthorized access to server functions.
The technical flaw exploits a fundamental weakness in input validation and command parsing within the Hastymail application's SMTP handling code. When the application processes email messages, it fails to properly sanitize or validate the smtp_message parameter, particularly in scenarios where the parameter contains the specific CRLF.CRLF sequence that typically signifies the end of SMTP message data. This parsing error creates a privilege escalation opportunity where authenticated users can inject commands that would normally be restricted when attempting to establish direct SMTP sessions. The vulnerability essentially allows for a form of command injection that operates outside the normal boundaries of user privileges, as the SMTP server configuration that normally prevents direct session establishment becomes ineffective when the malicious commands are embedded within the message parameter.
The operational impact of this vulnerability extends beyond simple message processing, as it enables attackers to potentially perform unauthorized actions on the mail server. Remote authenticated users can leverage this weakness to send commands that might allow them to access server resources, modify email configurations, or even gain access to other users' email accounts. The cross-privilege boundary aspect of this vulnerability is particularly concerning because it undermines the security model that typically separates user access from direct server control. This type of vulnerability can lead to data breaches, unauthorized email forwarding, server compromise, and potential lateral movement within network environments where the mail server serves as a central communication hub. The vulnerability is classified under CWE-94, which represents "Improper Control of Generation of Code ('Code Injection')" and aligns with ATT&CK techniques related to command execution and privilege escalation.
The security implications of CVE-2006-5313 are particularly severe in environments where mail servers handle sensitive communications and where proper access controls are essential. Organizations using affected versions of Hastymail should immediately implement the vendor-provided patch released on October 8, 2006, which addresses the input validation issues in the SMTP message handling component. Additionally, system administrators should review SMTP server configurations to ensure that appropriate access controls are in place and consider implementing network-level restrictions to limit the exposure of mail server services. The vulnerability demonstrates the importance of proper input sanitization and the potential risks associated with applications that process user-supplied data without adequate validation, particularly in contexts where such data can influence server-side operations. Organizations should also conduct thorough security assessments of their email infrastructure to identify similar vulnerabilities in other applications and ensure that appropriate security controls are in place to prevent unauthorized command execution within their mail systems.