CVE-2013-4073 is sort of related, but it doesn\t really explain what's being fixed here.
diff --git a/ChangeLog b/ChangeLog
index 94d852e..6d71417 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,8 @@
2013-08-11 Christian Heimes <christian@python.org>
* OpenSSL/crypto/x509ext.c: Fix handling of NULL bytes inside
- subjectAltName general names, CVE-2013-4073.
+ subjectAltName general names when formatting an X509 extension
+ as a string.
* OpenSSL/crypto/x509.c: Fix memory leak in get_extension().
2011-08-14 Jean-Paul Calderone <exarkun@twistedmatrix.com>