CRITICAL

CVE-2026-64620

FreeRDP before 3.28.0 Heap Buffer Overflow via crypto_rsa_common

CVSS v3

9.8

CRITICAL

EPSS Score

exploit probability

CISA KEV

No

known exploited

Exploitation

SSVC status

Description

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 serv

Technical details

CVSS v3 Vector
3.1
Published
7/20/2026
Last Modified
7/20/2026

Frequently asked questions

What is CVE-2026-64620?

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 serv

Is CVE-2026-64620 actively exploited?

Active exploitation of CVE-2026-64620 has not been confirmed. The EPSS score is N/A%, indicating the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-64620?

CVE-2026-64620 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string 3.1.

Is CVE-2026-64620 affecting your environment?

Use isMalicious to check if any of your IPs or domains are associated with this vulnerability's IOCs.