An issue was discovered in Mbed TLS before 2.28.2 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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2022-35409
• https://github.com/Mbed-TLS/mbedtls/releases
• https://mbed-tls.readthedocs.io/en/latest/security-advisories/advisories/mbedtls-security-advisory-2022-07.html
• https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html