This affects all users who use the RSA encryption, decryption, sign and verify APIs.
The function mbedtls_rsa_init() no longer supports selecting the PKCS#1 v2.1 encoding and its hash. It just selects the PKCS#1 v1.5 encoding by default. If you were using the PKCS#1 v2.1 encoding you now need, subsequently to the call to mbedtls_rsa_init(), to call mbedtls_rsa_set_padding() to set it.
To choose the padding type when initializing a context, instead of
mbedtls_rsa_init(ctx, padding, hash_id);
, use
mbedtls_rsa_init(ctx); mbedtls_rsa_set_padding(ctx, padding, hash_id);
To use PKCS#1 v1.5 padding, instead of
mbedtls_rsa_init(ctx, MBEDTLS_RSA_PKCS_V15, <ignored>);
, just use
mbedtls_rsa_init(ctx);