CVE-2026-64620 (GCVE-0-2026-64620)
Vulnerability from cvelistv5 – Published: 2026-07-20 12:04 – Updated: 2026-07-21 11:08
VLAI
EPSS
VEX
Title
FreeRDP before 3.28.0 Heap Buffer Overflow via crypto_rsa_common
Summary
FreeRDP before 3.28.0 (affected <=3.27.1) contains a heap-based buffer overflow in crypto_rsa_common() (libfreerdp/crypto/crypto.c). The function writes the modular-exponentiation result into the caller's output buffer via BN_bn2bin() and only afterward checks output_length > 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.
Severity
9.8 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-20 19:27 UTC
CWE
- CWE-122 - Heap-based Buffer Overflow
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/FreeRDP/FreeRDP/security/advis… | vendor-advisory |
| https://github.com/FreeRDP/FreeRDP/commit/1f7a716… | patch |
| https://www.vulncheck.com/advisories/freerdp-befo… | third-party-advisory |
Impacted products
Date Public
2026-07-06 00:00
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