Reachable assertion in FreeRDP - CVE-2026-121407
Published: November 10, 2026 / Updated: November 11, 2026
Vulnerability identifier: #VU164438
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-121407
CWE-ID: CWE-617
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service by aborting assertion-enabled FreeRDP shadow servers and disconnecting their sessions.
The vulnerability exists due to an inverted PDU completeness comparison and improper stream-capacity handling in remdesk_server_thread when processing channel data. A remote user can join the remdesk static virtual channel and send an 8192-byte payload with eight initial zero bytes declaring an eight-byte PDU to trigger a fatal Stream_Seek capacity assertion.
Affected software
FreeRDP
How to mitigate CVE-2026-121407
Install security update from vendor's website.
FreeRDP - update to 3.32.2