OpenSSL is vulnerable to a denial of service, caused by a NULL pointer dereference in signature_algorithms processing. By sending a specially crafted renegotiation ClientHello message from a client, a remote attacker could exploit this vulnerability to cause the TLS server to crash.
OpenSSL could allow a remote attacker to bypass security restrictions, caused by a a missing check in the validation logic of X.509 certificate chains by the X509_V_FLAG_X509_STRICT flag. By using any valid certificate or certificate chain to sign a specially crafted certificate, an attacker could bypass the check that non-CA certificates must not be able to issue other certificates and override the default purpose.
Refer to OpenSSL Security Advisory for patch, upgrade or suggested workaround information.