CVE-2026-31806
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk47th percentile - higher than 47% of all known CVEs
Summary
In FreeRDP prior to 3.24.0, the gdi_surface_bits() function fails to properly validate bmp.width and bmp.height values from the RDP server. A malicious server can supply crafted values exceeding the surface size, causing a heap buffer overflow during bitmap decoding. The attacker controls pixel data, potentially overwriting adjacent heap memory.
Risk Assessment
The organization is at risk of remote code execution via a malicious RDP server, potentially leading to client compromise and lateral movement within the internal network.
Recommendation
Upgrade FreeRDP to version 3.24.0 or later immediately. As a workaround, restrict RDP connections to trusted servers only.
Original NVD description (English source)
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, the gdi_surface_bits() function processes SURFACE_BITS_COMMAND messages sent by the RDP server. When the command is handled using NSCodec, the bmp.width and bmp.height values provided by the server are not properly validated against the actual desktop dimensions. A malicious RDP server can supply crafted bmp.width and bmp.height values that exceed the expected surface size. Because these values are used during bitmap decoding and memory operations without proper bounds checking, this can lead to a heap buffer overflow. Since the attacker can also control the associated pixel data transmitted by the server, the overflow may be exploitable to overwrite adjacent heap memory. This vulnerability is fixed in 3.24.0.