mbedtls: local side channel attack on classical CBC decryption in (D)TLS (CVE-2020-16150)

A Lucky 13 timing side channel in mbedtls_ssl_decrypt_buf in library/ssl_msg.c in Trusted Firmware Mbed TLS through 2.23.0 allows an attacker to recover secret key information. This affects CBC mode because of a computed time difference based on a padding length.

Fixed In Version:

mbedtls 2.24.0, 2.16.8 or 2.7.17

References:

• https://tls.mbed.org/tech-updates/security-advisories/mbedtls-security-advisory-2020-09-1
• https://nvd.nist.gov/vuln/detail/CVE-2020-16150

Affected branches:

• master
• 3.12-stable
• 3.11-stable
• 3.10-stable