This is a 48+ hours heads up, so UnrealIRCd admins know they should be around to patch their server on Saturday:
Internally we discovered a serious issue in UnrealIRCd. In a common configuration scenario, a regular user can cause UnrealIRCd to crash, which results in all users being disconnected from the server. This issue is present in all recent UnrealIRCd releases (the latest 6.1.3, but also older ones are affected). At the moment, the risk seems limited to a crash only, at least on all tested commonly used Linux variants.
A fixed version, UnrealIRCd 6.1.4, will be released on Saturday, December 16, 2023, at 16:00 GMT
At the same date/time we will also release a "hot patch" so *NIX users can fix the issue without restart.
When the fix comes out on Saturday, we suggest admins on *NIX to apply the patch immediately (which is possible without downtime and only takes a minute) or to upgrade quickly to UnrealIRCd 6.1.4 (e.g. when on Windows or if you just feel like upgrading). This is also the reason for sending out this pre-announcement with an exact date and time. This way people can be "ready" and fix things immediately, minimizing the time for bad people potentially crashing IRC servers.
Please understand that until the release at Saturday we cannot provide any further information.