Hackers have exploited a security vulnerability in Brevo, a marketing platform, to inject malware into around 100,000 websites. The attackers gained access using a compromised API key, which allowed them to deploy a Cloudflare worker that inserted malicious scripts into the affected sites. This incident raises significant concerns for website owners who may not be aware of the breach, as the injected malware could compromise user data or lead to further attacks. Users visiting these compromised sites could potentially be exposed to a range of threats, including data theft or malware infections. It’s crucial for those using the Brevo platform to take immediate action to secure their websites and protect their users.