From 8f964d4677009acf943bfdcaf90cfb98b4031730 Mon Sep 17 00:00:00 2001 From: Gilles Peskine Date: Mon, 17 Feb 2025 17:49:20 +0100 Subject: [PATCH] Changelog entries for requiring mbedls_ssl_set_hostname() in TLS clients Signed-off-by: Gilles Peskine --- ChangeLog.d/mbedtls_ssl_set_hostname.txt | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) create mode 100644 ChangeLog.d/mbedtls_ssl_set_hostname.txt diff --git a/ChangeLog.d/mbedtls_ssl_set_hostname.txt b/ChangeLog.d/mbedtls_ssl_set_hostname.txt new file mode 100644 index 0000000000..cb61ed18e8 --- /dev/null +++ b/ChangeLog.d/mbedtls_ssl_set_hostname.txt @@ -0,0 +1,18 @@ +Default behavior changes + * In TLS clients, if mbedtls_ssl_set_hostname() has not been called, + mbedtls_ssl_handshake() now fails with + MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME + if certificate-based authentication of the server is attempted. + This is because authenticating a server without knowing what name + to expect is usually insecure. To restore the old behavior, either + call mbedtls_ssl_set_hostname() with NULL as the hostname, or + enable the new compile-time option + MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME. + +Security + * Note that TLS clients should generally call mbedtls_ssl_set_hostname() + if they use certificate authentication (i.e. not pre-shared keys). + Otherwise, in many scenarios, the server could be impersonated. + The library will now prevent the handshake and return + MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME + if mbedtls_ssl_set_hostname() has not been called.