CVE-2006-5552 in RevilloC MailServer
Summary
by MITRE
Multiple heap-based buffer overflows in RevilloC MailServer 1.21 and earlier allow remote attackers to cause a denial of service (CPU consumption or application crash) or execute arbitrary code via a long argument to the (1) MAIL FROM or (2) RCPT TO command.
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Analysis
by VulDB Data Team • 04/25/2026
The vulnerability described in CVE-2006-5552 represents a critical heap-based buffer overflow flaw affecting RevilloC MailServer version 1.21 and earlier implementations. This vulnerability exists within the mail server's handling of SMTP commands, specifically targeting the MAIL FROM and RCPT TO command processing mechanisms that are fundamental to email transmission protocols. The flaw stems from inadequate input validation and bounds checking within the server's SMTP protocol implementation, creating exploitable conditions where maliciously crafted arguments can exceed allocated memory buffers.
The technical nature of this vulnerability manifests as heap-based buffer overflows, which occur when the mail server fails to properly validate the length of arguments passed to SMTP commands during the email transmission process. When an attacker sends a specially crafted long argument to either the MAIL FROM or RCPT TO commands, the server's memory allocation routines cannot accommodate the excessive data, leading to memory corruption within the heap allocation space. This memory corruption can result in unpredictable program behavior including application crashes, infinite loops causing excessive cpu consumption, or in more severe cases, arbitrary code execution within the context of the mail server process.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution capabilities. Attackers can exploit this weakness to gain unauthorized control over the mail server system, potentially leading to complete system compromise. The vulnerability affects the core functionality of email services, making it particularly dangerous for organizations relying on these mail servers for business communications. The heap-based nature of the overflow means that exploitation could lead to stack smashing or memory corruption that might be leveraged to execute malicious payloads through carefully crafted input sequences.
From a cybersecurity perspective, this vulnerability aligns with CWE-121 Heap-based Buffer Overflow, which specifically addresses buffer overflows occurring in heap memory allocations. The attack vector represents a classic remote exploitation scenario that falls under ATT&CK technique T1203, specifically targeting remote services through protocol manipulation. The vulnerability demonstrates the critical importance of input validation and proper bounds checking in network services, particularly those handling user-provided data through standard protocols. Organizations should implement immediate mitigation measures including patching the mail server software to version 1.22 or later, implementing network segmentation to limit access to mail server services, and deploying intrusion detection systems to monitor for exploitation attempts. Additionally, regular security assessments of mail server configurations and implementation of proper memory protection mechanisms such as stack canaries and address space layout randomization should be considered as part of comprehensive security hardening efforts.