Several media outlets have followed up: Bitcoin Lightning Network Development Kit (LDK) fixes a vulnerability that could put funds at risk of theft; production users are advised to upgrade
Bad news can come suddenly, and the market's initial reaction is often an overreaction. Staying calm matters more than anything.
$BTC Currently at 82686.72 (24h -1.22%). Given the timing, this news broke during trading, so its impact may be felt sooner.