CVE-2026-121396

A flaw was found in FreeRDP. A remote attacker operating a malicious Remote Desktop (RD) Gateway can cause a denial of service (DoS) by sending a crafted Request to Send (RTS) packet with malformed authentication padding. When parsed, this invalid padding triggers an internal assertion failure that abruptly terminates the connecting client process. This flaw only affects FreeRDP clients built with the WITH_VERBOSE_WINPR_ASSERT flag enabled.

Red Hat Enterprise Linux ships FreeRDP with WITH_VERBOSE_WINPR_ASSERT disabled (not set in RHEL 9, explicitly set to OFF in RHEL 10), so the vulnerable assertion is a no-op in production packages. RHEL systems are not affected by this vulnerability.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.