lib/pk-libgcrypt.c in libgnutls in GnuTLS before 2.6.6 does not properly handle invalid DSA signatures, which allows remote attackers to cause a denial of service (application crash) and possibly have unspecified other impact via a malformed DSA key that triggers a (1) free of an uninitialized pointer or (2) double free.
https://exchange.xforce.ibmcloud.com/vulnerabilities/50445
https://exchange.xforce.ibmcloud.com/vulnerabilities/50260