Reachable assertion in FreeRDP - #VU156173
Published: October 19, 2026
Vulnerability identifier: #VU156173
CSH Severity: Medium
CVSS v4: 6.7 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
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 client process.
The vulnerability exists due to a reachable assertion in the FreeRDP RemoteFX differential decoder when processing crafted RemoteFX tile data. A remote attacker can entice a victim to connect to a malicious RDP server and send a tile containing two adjacent LL3 coefficients of 20,000 each, whose sum of 40,000 fails a signed 16-bit range assertion, to abort the client process.
Exploitation requires a client build with verbose WinPR assertions enabled (WITH_VERBOSE_WINPR_ASSERT=ON) and a server that negotiates the classic RemoteFX surface-bits path.
Affected software
FreeRDP
Remediation
Install security update from vendor's website.
FreeRDP - update to 3.32.2