BUF-PL-SA-2016 Irssi Security Advisory 
information disclosure vulnerability in buf.pl
An information disclosure vulnerability was found, reported and fixed in the buf.pl script by its author.
Information disclosure vulnerability found by Juerd Waalboer. (CWE-732, CWE-538)
CVE-2016-7553  was assigned to this issue.
Other users on the same machine may be able to retrieve the whole window contents after /UPGRADE when the buf.pl script is loaded. Furthermore, this dump of the windows contents is never removed afterwards.
Since buf.pl is also an Irssi core script and we recommended its use to retain your window content, many people could potentially be affected by this.
Remote users may be able to retrieve these contents when combined with other path traversal vulnerabilities in public facing services on that machine.
- All buf.pl versions that we observed
Update the buf.pl script with the latest version from https://scripts.irssi.org
- Careful users with a limited umask (e.g. 077) are not affected by this bug. However, most Linux systems default to a umask of 022, meaning that files written without further restricting the permissions, are readable by any user.
- buf.pl restores the scrollbuffer between “/upgrade”s by writing the contents to a file, and reading that after the new process was spawned. Through that file, the contents of (private) chat conversations may leak to other users.