GnuPG 1.4.x, 2.0.x, and 2.1.x treats a key flags subpacket with all bits cleared (no usage permitted) as if it has all bits set (all usage permitted), which might allow remote attackers to bypass intended cryptographic protection mechanisms by leveraging the subkey.
GnuPG before 1.4.14, and Libgcrypt before 1.5.3 as used in GnuPG 2.0.x and possibly other products, allows local users to obtain private RSA keys via a cache side-channel attack involving the L3 cache, aka Flush+Reload.
The read_block function in g10/import.c in GnuPG 1.4.x before 1.4.13 and 2.0.x through 2.0.19, when importing a key, allows remote attackers to corrupt the public keyring database or cause a denial of service (application crash) via a crafted length field of an OpenPGP packet.