Incorrect offset calculation leading to denial of service in FreeRDP

FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license. This issue affects Clients only. Integer underflow leading to DOS (e.g. abort due to WINPR_ASSERT with default compilation flags). When an insufficient blockLen is provided, and proper length validation is not performed, an Integer Underflow occurs, leading to a Denial of Service (DOS) vulnerability. This issue has been addressed in versions 2.11.0 and 3.0.0-beta3. Users are advised to upgrade. There are no known workarounds for this vulnerability.