Linux Mint forum database compromised, all users urged to change passwords
blog.linuxmint.com
blog.linuxmint.com
The DNS Hijack by pre-installing OpenDNS on all installations is one of those cases: https://bugs.launchpad.net/linuxmint/+bug/1133777
> "An encrypted copy of your forums password"
Likely is just a non-technical wording for "Your salted and hashed passwords" (yes, I don't like it either... but keep in mind the audience)
I never used the linuxmint forums, but by looking on the google cache (since the forums are down)
http://webcache.googleusercontent.com/search?q=cache:IxvZKvC...
It's obvious that they're using phpbb. Just like wordpress, and other prominent software written in php it has probably several flaws (security or otherwise), so I'd still steer clear of it... but it's safe to assume that in 2016 a major open source project has learnt how to properly salt and hash their passwords...
In fact, they're using bcrypt:
https://github.com/phpbb/phpbb/tree/3.1.x/phpBB/phpbb/passwo...
I don't know if this is the default hashing algorithm, and if they're properly salting them... it's even possible that linuxmint forums are misconfigured and/or that they're using an old version that defaults on md5.
But even if you use Argon2 or Scrypt, it won't do you any good if you picked
"Password1!"
or
"onetwothreefourfivesix"
as a password... it _will_ be cracked! (and thus the suggestion of changing passwords that might have been reused on other services is a perfectly good suggestion)
Regarding your other point, just because someone uses an algorithm doesn't mean that it is used with proper parameters, work factors, etc.
Do no make any assumptions about crypto, "probably using" is not good enough.
Based on the date, they might have been using a fairly old version of phpBB 3.