Urgent: Update required for Electrum
Because the Electrum wallet is open source, a number of altcoin wallets have been developed that display the same vulnerability, such as Electron Cash. For these wallets, the same advice applies: Do not open the wallet. Wait until an update is released for the wallet.
If at any time you had an older version of the Electrum wallet open without a password and a web page open at the same time, the possibility can’t be excluded that someone has access to the bitcoins on your wallet. To exclude this risk, it’s recommendable to make a new wallet in Electron or another wallet program and to send the Bitcoins to this new wallet.
Note: This issue only applies to the Electrum wallet. There is as of yet no reason to assume users of other Bitcoin wallets face similar security risks.