When receiving a DCC file, the filename built contains the remote nick (the option xfer.file.use_nick_in_filename is on by default).
If the nick contains special characters, the file could be written outside of the configured download path.
Xfer never overwrites existing files, so if a file exists with the same name, a suffix like ".1" is appended to the filename.
Mitigation
Turn off option to include nick in filename: /set xfer.file.use_nick_in_filename off.
Credit
The issue was discovered by aizu-m.
WSA-2024-1: [Core, Plugins] Integer overflow in loops on lists.
An integer overflow can happen when looping over items in a list.
This can only happen in rare conditions on 32 and 64-bit systems, as the list must contain more than 2,147,483,647 elements.
On 16-bit systems, this happens with a list that contains more than 32,767 elements.
Mitigation
There is no known mitigation.
The upgrade to the latest stable version is highly recommended.
Credit
The issue was discovered by Yiheng Cao.
WSA-2013-2: [IRC] Crash on send of unknown commands to IRC server.
Untrusted command for function hook_process could lead to execution of commands, because of shell expansions (so the problem is only caused by some scripts, not by WeeChat itself).
Mitigation
Remove/unload all scripts calling the API function hook_process.
WSA-2011-1: [IRC] Possible man-in-the-middle attack in TLS connection to IRC server.