python-gnupg is a command-line program which provides support for programmatic access via spawning a separate process to run it and then communicating with that process from your program.
Affected versions of this package are vulnerable to Improper Input Validation.
An attacker can inject data through the passphrase property of the
gnupg.GPG.decrypt() methods when symmetric encryption is used.
The supplied passphrase is not validated for newlines, and the library passes
--passphrase-fd=0 to the gpg executable, which expects the passphrase on the first line of stdin, and the ciphertext to be decrypted or plaintext to be encrypted on subsequent lines.
By supplying a passphrase containing a newline an attacker can control/modify the ciphertext/plaintext being decrypted/encrypted.
python-gnupg to version 0.4.4 or higher.