CVE-2026-31806: freerdp Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-31806 is a critical (CVSS 9.8) Heap-based Buffer Overflow vulnerability in freerdp. EPSS estimates a 0.67% chance of exploitation in the next 30 days, higher than 51% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 13-03-2026
   PublishedVulnerability first disclosed.
2. 15-07-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
• CWE-131Incorrect Calculation of Buffer SizeThe product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.