Changes between 1.0.2e and 1.0.2f [xx XXX xxxx]
+ *) DH small subgroups
+
+ Historically OpenSSL only ever generated DH parameters based on "safe"
+ primes. More recently (in version 1.0.2) support was provided for
+ generating X9.42 style parameter files such as those required for RFC 5114
+ support. The primes used in such files may not be "safe". Where an
+ application is using DH configured with parameters based on primes that are
+ not "safe" then an attacker could use this fact to find a peer's private
+ DH exponent. This attack requires that the attacker complete multiple
+ handshakes in which the peer uses the same private DH exponent. For example
+ this could be used to discover a TLS server's private DH exponent if it's
+ reusing the private DH exponent or it's using a static DH ciphersuite.
+
+ OpenSSL provides the option SSL_OP_SINGLE_DH_USE for ephemeral DH (DHE) in
+ TLS. It is not on by default. If the option is not set then the server
+ reuses the same private DH exponent for the life of the server process and
+ would be vulnerable to this attack. It is believed that many popular
+ applications do set this option and would therefore not be at risk.
+
+ The fix for this issue adds an additional check where a "q" parameter is
+ available (as is the case in X9.42 based parameters). This detects the
+ only known attack, and is the only possible defense for static DH
+ ciphersuites. This could have some performance impact.
+
+ Additionally the SSL_OP_SINGLE_DH_USE option has been switched on by
+ default and cannot be disabled. This could have some performance impact.
+
+ This issue was reported to OpenSSL by Antonio Sanso (Adobe).
+ (CVE-2016-0701)
+ [Matt Caswell]
+
+ *) SSLv2 doesn't block disabled ciphers
+
+ A malicious client can negotiate SSLv2 ciphers that have been disabled on
+ the server and complete SSLv2 handshakes even if all SSLv2 ciphers have
+ been disabled, provided that the SSLv2 protocol was not also disabled via
+ SSL_OP_NO_SSLv2.
+
+ This issue was reported to OpenSSL on 26th December 2015 by Nimrod Aviram
+ and Sebastian Schinzel.
+ (CVE-2015-3197)
+ [Viktor Dukhovni]
+
*) Reject DH handshakes with parameters shorter than 1024 bits.
[Kurt Roeckx]