CVE-2026-64620
Severity CVSS v4.0:
CRITICAL
Type:
CWE-122
Heap-based Buffer Overflow
Publication date:
20/07/2026
Last modified:
23/07/2026
Description
FreeRDP before 3.28.0 (affected out_length, so out-of-bounds bytes are written before the bounds check. On the server side, when a client selects RDP Standard Security, the encrypted client random is decrypted into a fixed 32-byte buffer. Because the server publishes its RSA public key, an unauthenticated attacker can forge a ciphertext whose decrypted value is up to the full modulus length (e.g. 256 bytes for RSA-2048), overflowing the 32-byte heap buffer by up to ~224 attacker-controlled bytes pre-authentication, resulting in denial of service.
Impact
Base Score 4.0
9.30
Severity 4.0
CRITICAL
Base Score 3.x
9.80
Severity 3.x
CRITICAL