gpg (aka GnuPG) 1.0.4 and other versions does not properly verify detached signatures, which allows attackers to modify the contents of a file without detection.
distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000368
www.debian.org/security/2000/20001225b
www.linux-mandrake.com/en/updates/2000/MDKSA-2000-087.php3
www.osvdb.org/1699
www.redhat.com/support/errata/RHSA-2000-131.html
www.securityfocus.com/archive/1/152197
www.securityfocus.com/bid/2141
exchange.xforce.ibmcloud.com/vulnerabilities/5802