CVE-2026-40033: freerdp Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-40033 is a high (CVSS 8.8) Heap-based Buffer Overflow vulnerability in freerdp. EPSS estimates a 1.06% chance of exploitation in the next 30 days, higher than 64.1% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 26-05-2026
   PublishedVulnerability first disclosed.
2. 27-07-2026
   Last modifiedVulnerability information updated.

Description

FreeRDP before 3.26.0 contains a heap-buffer-overflow vulnerability in gdi_CacheToSurface that allows remote attackers to write out-of-bounds heap memory. The vulnerability occurs because rectangle validation clamps coordinates to UINT16_MAX but performs copy operations using unclamped cache entry dimensions, enabling malicious RDP servers to trigger large out-of-bounds writes and potentially achieve remote code execution or client crash.

• 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-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.