CVE-2020-7845 in Spamsniper
Summary
by MITRE • 12/27/2020
Spamsniper 5.0 ~ 5.2.7 contain a stack-based buffer overflow vulnerability caused by improper boundary checks when parsing MAIL FROM command. It leads remote attacker to execute arbitrary code via crafted packet.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 05/29/2026
The Spamsniper email security appliance versions 5.0 through 5.2.7 contain a critical stack-based buffer overflow vulnerability that arises from inadequate input validation during parsing of the MAIL FROM SMTP command. This vulnerability represents a classic software flaw where the application fails to properly verify the boundaries of user-supplied data before copying it into fixed-size memory buffers. The flaw exists within the SMTP protocol handling mechanism, specifically when processing the MAIL FROM command which is fundamental to email transmission and represents one of the earliest commands in the SMTP transaction process.
The technical implementation of this vulnerability stems from the application's failure to perform proper bounds checking on the mailbox address parameter provided in the MAIL FROM command. When a remote attacker crafts a malicious packet containing an excessively long mailbox address string, the application attempts to copy this data into a stack buffer without validating whether the input exceeds the allocated buffer size. This condition creates a classic stack overflow scenario where the excess data overwrites adjacent memory locations including return addresses and control information. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory allocations where insufficient boundary checks allow data to overwrite adjacent memory regions.
The operational impact of this vulnerability is severe as it provides remote attackers with the capability to execute arbitrary code on the affected system with the privileges of the running service. An attacker can exploit this vulnerability by sending a specially crafted SMTP MAIL FROM command containing a buffer overflow payload, potentially leading to complete system compromise including privilege escalation, data exfiltration, and persistent access. The attack vector requires only network connectivity to the Spamsniper appliance and does not require authentication, making it particularly dangerous in environments where email security appliances are exposed to untrusted networks. This vulnerability directly maps to ATT&CK technique T1190 Exploit Public-Facing Application, as it represents an exploitation of a vulnerability in a publicly accessible email security service.
Mitigation strategies for this vulnerability include immediate application of vendor patches or firmware updates that implement proper input validation and boundary checking mechanisms. Organizations should also implement network segmentation to limit access to email security appliances and deploy intrusion detection systems to monitor for suspicious SMTP traffic patterns. The solution requires enforcing strict input length limits on MAIL FROM command parameters and implementing stack protection mechanisms such as stack canaries or address space layout randomization. Additionally, administrators should consider implementing SMTP protocol filtering rules that reject excessively long mailbox addresses and monitor for anomalous email traffic patterns that may indicate exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar flaws in other email processing components and ensure comprehensive protection against similar attack vectors.