pinentry is a collection of simple PIN or passphrase entry dialogs which utilize the Assuan protocol.
Tavis Ormandy of the Gentoo Linux Security Audit Team has discovered that the pinentry ebuild incorrectly sets the permissions of the pinentry binaries upon installation, so that the sgid bit is set making them execute with the privileges of group ID 0.
A user of pinentry could potentially read and overwrite files with a group ID of 0.
There is no known workaround at this time.
All pinentry users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-crypt/pinentry-0.7.2-r2"