An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms extension (where it was present in the initial ClientHello), but includes a signature_algorithms_cert extension then a NULL pointer dereference will result, leading to a crash and a denial of service attack. A server is only vulnerable if it has TLSv1.2 and renegotiation enabled (which is the default configuration). OpenSSL TLS clients are not impacted by this issue. All OpenSSL 1.1.1 versions are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1k. OpenSSL 1.0.2 is not impacted by this issue. Fixed in OpenSSL 1.1.1k (Affected 1.1.1-1.1.1j).

Affected devices do not properly handle the renegotiation of SSL/TLS parameters. This could allow an unauthenticated remote attacker to bypass the TCP brute force prevention and lead to a denial of service condition for the duration of the attack.

Affected devices do not properly sanitize an input field. This could allow an authenticated remote attacker with administrative privileges to inject code or spawn a system root shell.

Affected devices do not properly sanitize data introduced by an user when rendering the web interface. This could allow an authenticated remote attacker with administrative privileges to inject code and lead to a DOM-based XSS.