CVE-2006-5262 in Hastymail
Summary
by MITRE
CRLF injection vulnerability in lib/session.php in Hastymail 1.5 and earlier before 20061008 allows remote authenticated users to send arbitrary IMAP commands via a CRLF sequence in a mailbox name. NOTE: the attack crosses privilege boundaries if the IMAP server configuration prevents a user from establishing a direct IMAP session.
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Analysis
by VulDB Data Team • 04/24/2026
The CVE-2006-5262 vulnerability represents a critical CRLF injection flaw in the Hastymail webmail application that affects versions 1.5 and earlier. This vulnerability exists within the lib/session.php component and specifically targets the handling of mailbox names during IMAP session establishment. The flaw allows authenticated remote attackers to inject carriage return line feed sequences into mailbox name parameters, which can then be processed by the underlying IMAP server. This type of vulnerability falls under CWE-115, which categorizes improper handling of CRLF sequences in input validation contexts, and demonstrates the dangerous intersection of web application security and protocol-level vulnerabilities. The vulnerability is particularly concerning because it operates at the boundary between web application logic and network protocol handling, creating a pathway for attackers to manipulate IMAP commands through seemingly benign input fields.
The technical exploitation of this vulnerability occurs when an authenticated user submits a mailbox name containing CRLF sequences that are not properly sanitized or escaped before being transmitted to the IMAP server. These sequences can cause the IMAP server to interpret additional commands that follow the injected CRLF characters, effectively allowing the attacker to execute arbitrary IMAP commands within the context of the authenticated session. The attack vector specifically targets the session management component where mailbox names are processed, and the vulnerability is particularly dangerous because it can cross privilege boundaries. When an IMAP server is configured to restrict direct IMAP sessions for users, this vulnerability becomes even more impactful as it allows attackers to potentially escalate privileges or access restricted mailboxes through the application layer rather than direct protocol access.
The operational impact of CVE-2006-5262 extends beyond simple data access, as it can enable attackers to perform various malicious activities including reading, modifying, or deleting email messages, accessing other users' mailboxes, and potentially gaining unauthorized access to sensitive information. The vulnerability essentially provides a backdoor mechanism for attackers to bypass normal access controls and execute commands that would normally be restricted. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command injection and privilege escalation, specifically targeting the T1059.007 (Command and Scripting Interpreter: PowerShell) and T1548.001 (Abuse of Functionality) tactics. The vulnerability also aligns with T1190 (Exploit Public-Facing Application) as it represents an authenticated attack vector against a web application component that interfaces with network protocols.
Mitigation strategies for CVE-2006-5262 must address both the immediate vulnerability and broader security practices. The most direct solution involves patching the Hastymail application to version 20061008 or later, which contains the necessary input sanitization fixes. Organizations should implement comprehensive input validation and sanitization measures for all user-supplied data that gets processed by protocol-level components, particularly focusing on the prevention of CRLF sequences in mailbox names and other IMAP parameter fields. Additionally, network segmentation and access controls should be implemented to limit the potential impact of such vulnerabilities, ensuring that even if an attacker successfully exploits this vulnerability, they cannot access sensitive resources beyond their intended scope. The vulnerability also highlights the importance of proper security testing including input validation testing and protocol-level security reviews to identify similar injection flaws in other applications that interface with network protocols.