HCL Notes versions previous to releases 9.0.1 FP10 IF8, 10.0.1 FP6 and 11.0.1 FP1 is susceptible to a Stored Cross-site Scripting (XSS) vulnerability. An attacker could use this vulnerability to execute script in a victim's Web browser within the security context of the hosting Web site and/or steal the victim's cookie-based authentication credentials.

HCL Notes is susceptible to a Buffer Overflow vulnerability in DXL due to improper validation of user input. A successful exploit could enable an attacker to crash Notes or execute attacker-controlled code on the client system.

In HCL Notes version 9 previous to release 9.0.1 FixPack 10 Interim Fix 8, version 10 previous to release 10.0.1 FixPack 6 and version 11 previous to 11.0.1 FixPack 1, a vulnerability in the input parameter handling of the Notes Client could potentially be exploited by an attacker resulting in a buffer overflow. This could enable an attacker to crash HCL Notes or execute attacker-controlled code on the client.