openssl: multiple issues

• CVE-2015-1788 (denial of service)

When processing an ECParameters structure OpenSSL enters an infinite
loop if the curve specified is over a specially malformed binary
polynomial field.
This can be used to perform denial of service against any system which
processes public keys, certificate requests or certificates. This
includes TLS clients and TLS servers with client authentication enabled.

• CVE-2015-1789 (out-of-bounds read)

X509_cmp_time does not properly check the length of the ASN1_TIME string
and can read a few bytes out of bounds. In addition, X509_cmp_time
accepts an arbitrary number of fractional seconds in the time string.
An attacker can use this to craft malformed certificates and CRLs of
various sizes and potentially cause a segmentation fault, resulting in a
DoS on applications that verify certificates or CRLs. TLS clients that
verify CRLs are affected. TLS clients and servers with client
authentication enabled may be affected if they use custom verification
callbacks.

• CVE-2015-1790 (denial of service)

The PKCS#7 parsing code does not handle missing inner EncryptedContent
correctly. An attacker can craft malformed ASN.1-encoded PKCS#7 blobs
with missing content and trigger a NULL pointer dereference on parsing.
Applications that decrypt PKCS#7 data or otherwise parse PKCS#7
structures from untrusted sources are affected. OpenSSL clients and
servers are not affected.

• CVE-2015-1791 (double free)

If a NewSessionTicket is received by a multi-threaded client when
attempting to reuse a previous ticket then a race condition can occur
potentially leading to a double free of the ticket data.

• CVE-2015-1792 (denial of service)

When verifying a signedData message the CMS code can enter an infinite
loop if presented with an unknown hash function OID.
This can be used to perform denial of service against any system which
verifies signedData messages using the CMS code.

• CVE-2015-4000 (cipher downgrade)

A vulnerability in the TLS protocol allows a man-in-the-middle attacker
to downgrade vulnerable TLS connections using ephemeral Diffie-Hellman
key exchange to 512-bit export-grade cryptography. This vulnerability is
known as Logjam.
OpenSSL has added protection for TLS clients by rejecting handshakes
with DH parameters shorter than 768 bits. This limit will be increased
to 1024 bits in a future release.