The first security hole, tracked as CVE-2021-3450, has been described as a “problem with verifying a certificate chain when using the X509_V_FLAG_X509_STRICT flag.” The flaw was discovered by researchers at Akamai.

“Starting from OpenSSL version 1.1.1h a check to disallow certificates in the chain that have explicitly encoded elliptic curve parameters was added as an additional strict check. An error in the implementation of this check meant that the result of a previous check to confirm that certificates in the chain are valid CA certificates was overwritten. This effectively bypasses the check that non-CA certificates must not be able to issue other certificates,” the OpenSSL Project explained in its advisory.