Big security thing, please read.
Some modders' accounts were compromised on CurseForge, and have added malware to existing Minecraft mods.
As of about four hours ago, there have been reports of accounts of Minecraft modders being compromised, resulting in malware being added to certain mods/mod packs on CurseForge. If you get hit, your computer could eventually become part of a botnet, and you don't want that.
It's currently unknown what the goal of the botnet is, but current theories point towards at least one thing the malware will do is stealing Microsoft account tokens. Always assume it intends to do more.
If you've played modded Minecraft using CurseForge as your mod source recently, or Bukkit as your plugin source for servers, please very carefully read the links at the end of the post, ensure you weren't hit, and take any precautions mentioned within them if you feel comfortable doing so. If you don't, you need to get advice from someone you trust who has the ability to handle computer issues, and give them the information in the links.
If you feel comfortable doing so, you can attempt to nip it in the bud before it has a chance to run -- look for libWebGL64.jar on your system, and delete it. If you find it, I would also recommend a general scan for viruses and malware, because that means you ran one of the affected mods.
I would also advise you delete any of the affected mods/mod packs mentioned in either of the two following links, as those are what drop the libWebGL64.jar file in the first place. Of course, as always, back up your saves before doing anything mod related.
From the write-up, current advice is to consider any download from CurseForge or Bukkit's plugin repository to be potentially malicious, and investigate as noted above.
Primary: https://www.reddit.com/r/feedthebeast/comments/142zxka/some_curseforge_accounts_might_be/
Secondary: https://prismlauncher.org/news/cf-compromised-alert/
Technical write-up of the malware, currently being written: https://github.com/fractureiser-investigation/fractureiser