Heap-Based Buffer Overflow Vulnerability in Fortinet's FortiGate SSL VPN

Summary

CVE-2020-12819 is a high-risk heap-based buffer overflow vulnerability affecting FortiGate security appliances. This flaw is found in the processing of Link Control Protocol (LCP) messages, specifically in versions 5.6.12, 6.0.10, 6.2.4, and 6.4.1, as well as earlier releases. A malicious actor, possessing valid SSL VPN credentials, could exploit this vulnerability by sending a specially crafted large LCP packet while tunnel mode is enabled. The exploitation could lead to the crashing of the SSL VPN daemon, severely impacting the availability of the service. Although arbitrary code execution may be theoretically feasible, the practical risk under typical circumstances is considered low due to the complexity involved in executing such an attack. Users are urged to update their FortiGate software to mitigate this security issue.

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