Reachable assertion in FreeRDP - CVE-2026-121960
Published: November 10, 2026 / Updated: November 11, 2026
Vulnerability identifier: #VU164439
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-121960
CWE-ID: CWE-617
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service by terminating a FreeRDP shadow-server process and disconnecting its clients.
The vulnerability exists due to a reachable assertion in WinPrAsn1Decoder_InitMem when an NLA-enabled shadow server with assertions enabled passes a null negotiation buffer to the decoder after receiving a TSRequest without negoTokens. A remote attacker can send the seven-byte payload 30 05 a0 03 02 01 06 after RDP negotiation and the TLS handshake to trigger WINPR_ASSERT(source) and abort the server before authentication.
Affected software
FreeRDP
How to mitigate CVE-2026-121960
Install security update from vendor's website.
FreeRDP - update to 3.32.2