Status of RFC 8449 support

I saw the following comment when configuring Record Size Limit Extension (RFC 8449) in mbedtls_config.h [1]:

This extension is currently in development and must NOT be used except for testing purposes.

Is this still accurate? What functionality is missing for full RFC 8449 support? Is this feature planned for a specific date?

[1] mbedtls/include/mbedtls/mbedtls_config.h at 611f899c0c9d397baedfaec34ea0861ad2543991 · Mbed-TLS/mbedtls · GitHub


MbedTLS is not part of Mbed project anymore. How you can see the Mbed TLS category of Mbed support forum is not very active, also please look at this announcement about MbedTLS move to Mbed TLS ( .

BR, Jan

Thanks for the tip. I reposted the question on their mailing list here: