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.

The mpi_powm function in Libgcrypt before 1.6.3 and GnuPG before 1.4.19 allows attackers to obtain sensitive information by leveraging timing differences when accessing a pre-computed table during modular exponentiation, related to a "Last-Level Cache Side-Channel Attack."

In GnuPG before 2.5.17, a stack-based buffer overflow exists in tpm2daemon during handling of the PKDECRYPT command for TPM-backed RSA and ECC keys.

In GnuPG before 2.5.17, a crafted CMS (S/MIME) EnvelopedData message carrying an oversized wrapped session key can cause a stack-based buffer overflow in gpg-agent during PKDECRYPT--kem=CMS handling. This can easily be leveraged for denial of service; however, there is also memory corruption that could lead to remote code execution.

In GnuPG before 2.5.17, a long signature packet length causes parse_signature to return success with sig->data[] set to a NULL value, leading to a denial of service (application crash).