CVE-2026-54735: Prebid Server

Critical severity, CVSS 10.0. EPSS: 0.6% chance of exploitation in the next 30 days.

Prebid Server is an open-source solution for running real-time advertising auctions in the cloud. Prior to version 4.4.0, certain bidder adapters in Prebid Server interpolate user-supplied parameters into outbound request URLs without properly validating host and subdomain values, allowing crafted bid request parameters to cause server-side requests to unintended destinations and potentially expose internal network services or sensitive server endpoints. This issue is fixed in version 4.4.0.

Affected products

• Prebid Prebid Server: before 4.4.0 (fixed in 4.4.0)

Published 2026-07-29. Last modified 2026-08-18.