CVE-2022-35409: Arm Mbed TLS

Critical severity, CVSS 9.1. EPSS: 2.3% chance of exploitation in the next 30 days.

An issue was discovered in Mbed TLS before 2.28.1 and 3.x before 3.2.0. In some configurations, an unauthenticated attacker can send an invalid ClientHello message to a DTLS server that causes a heap-based buffer over-read of up to 255 bytes. This can cause a server crash or possibly information disclosure based on error responses. Affected configurations have MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE enabled and MBEDTLS_SSL_IN_CONTENT_LEN less than a threshold that depends on the configuration: 258 bytes if using mbedtls_ssl_cookie_check, and possibly up to 571 bytes with a custom cookie check function.

Affected products

• Arm Mbed TLS: before 2.28.1 (fixed in 2.28.1)
• Debian Debian Linux: version 10.0 only
• Trustedfirmware Mbed TLS: from 3.0.0, before 3.2.0 (fixed in 3.2.0)

Published 2022-07-15. Last modified 2026-06-17.