A vulnerability was found in the Electrum wallet software which potentially allows random websites to steal your wallet via JavaScript. The bug presumably also affects altcoin derivatives of Electrum such as Electron Cash. If you don't use Electrum or a derivative, then you are not affected and you can ignore this.
https://bitcointalk.org/index.php?topic=2702103.0
I actually really like the electrum wallets, they're one of the best in my opinion for bitcoin and litecoin. There is apparently an upgrade to fix the problem. We use them here locally for some auxiliary tasks. They're lightweight (don't require a lot of computing resources to use) so they're a great alternative to running a full node wallet, which uses quite a lot of hard disk space nowadays, but safer than using a web wallet (well, mostly safer, obviously there can be exceptions like this one).
I've temporarily shut down ours per the link above, and we'll upgrade tomorrow. The shutdown of these wallets doesn't affect our site in any way, we just use them for the occasional manual transaction to pay for something in crypto.