Brevo supply chain attack hits 100k+ sites with Wordpress backdoors and Clickfix malware
Attackers with Brevo DNS access injected malicious scripts serving ClickFix malware and WordPress backdoors to over 100,000 customer sites on 14 September 2026.
Brevo (formerly Sendinblue), an email marketing platform whose clients include eBay, Louis Vuitton, Michelin and Amnesty International, served injected JavaScript from sendibt1.com domains between 16:05 and 20:12 UTC on 14 September 2026, reaching over 100,000 customer sites and mailing lists. The f.js malware secretly installed a WordPress backdoor plugin from cdn10.sendibt1.com/p/wm.zip using logged-in admins' sessions and showed ClickFix overlays urging visitors to copy-paste and run commands. An SSL certificate for cdn.sendibt1.com created August 25 and attacker-created cdn* DNS records indicate write access to Brevo's Cloudflare DNS, likely via a single Cloudflare account compromise. Sansec recorded 2,549 CSP violation reports across 12 monitored sites; all malicious hosts stopped resolving on 15 September and Brevo's status page lists no incident.