Affected: GNU Libgcrypt, GnuPG

Libgcrypt before 1.6.3 and GnuPG before 1.4.19 does not implement ciphertext blinding for Elgamal decryption, which allows physically proximate attackers to obtain the server's private key by determining factors using crafted ciphertext and the fluctuations in the electromagnetic field during multiplication.

Affected: Ubuntu:14.04:LTS: gnupg, Ubuntu:14.04:LTS: gnupg2

Daniel Genkin, Lev Pachmanov, Itamar Pipman, and Eran Tromer discovered that GnuPG was susceptible to an attack via physical side channels. A local attacker could use this attack to possibly recover private keys. (CVE-2014-3591)

Daniel Genkin, Adi Shamir, and Eran Tromer discovered that GnuPG was susceptible to an attack via physical side channels. A local attacker could use this attack to possibly recover private keys. (CVE-2015-0837)

Hanno Böck discovered that GnuPG incorrectly handled certain malformed keyrings. If a user or automated system were tricked into opening a malformed keyring, a remote attacker could use this issue to cause GnuPG to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2015-1606, CVE-2015-1607)

In addition, this update improves GnuPG security by validating that the keys returned by keyservers match those requested.