An integer overflow vulnerability existed in the static function wolfssl_add_to_chain, that caused heap corruption when certificate data was written out of bounds of an insufficiently sized certificate buffer. wolfssl_add_to_chain is called by these API: wolfSSL_CTX_add_extra_chain_cert, wolfSSL_CTX_add1_chain_cert, wolfSSL_add0_chain_cert. These API are enabled for 3rd party compatibility features: enable-opensslall, enable-opensslextra, enable-lighty, enable-stunnel, enable-nginx, enable-haproxy. This issue is not remotely exploitable, and would require that the application context loading certificates is compromised.