The security advisory is at LWN.net: "Screen allows the user to overload the visual bell with a text message that
can be set by the user. This text message is handled as a format string,
instead of as a pure string, so maliciously written format strings are
allowed to overwrite the stack. Since screen in Red Hat Linux 5.2 and
earlier releases was setuid root, this security hole could be exploited to
gain a root shell."
September 16, 2000