openssl: man-in-the-middle

• CVE-2015-3197 (man-in-the-middle)

A flaw was found in the way malicious SSL/TLS clients could negotiate
SSLv2 ciphers that have been disabled on the server. This could result
in weak SSLv2 ciphers being used for SSL/TLS connections, making them
vulnerable to man-in-the-middle attacks.

• CVE-2015-4000 (man-in-the-middle)

A flaw was found in the way the TLS protocol composes the Diffie-Hellman
exchange (for both export and non-export grade cipher suites). An
attacker could use this flaw to downgrade a DHE connection to use
export-grade key sizes, which could then be broken by sufficient
pre-computation. This can lead to a passive man-in-the-middle attack in
which the attacker is able to decrypt all traffic.

• CVE-2016-0701 (man-in-the-middle)

It was found that OpenSSL used weak Diffie-Hellman parameters based on
unsafe primes, which were generated and stored in X9.42-style parameter
files. An attacker who could force the peer to perform multiple
handshakes using the same private DH component could use this flaw to
conduct man-in-the-middle attacks on the SSL/TLS connection.