Security
Advisory
In short and in plain language
An advisory is a security warning. Most of the time it is about a flaw in a program.
It then says which versions are affected and how serious the flaw is. It also says which version fixes the problem.
Agencies also use it to warn about new kinds of attacks.
Definition
An advisory is a security notice, usually about a vulnerability in a piece of software. Such an advisory typically names the affected versions, the severity and the version that contains the fix. Vendors, authorities and security databases publish such notices. Authorities also use advisories to warn about current attack methods, for example the approach of particular groups of attackers.