CVE-2026-54734 Prebid Server Java: Vulnerability to request forgery allows for possible host environment data extraction
Attackers can force the server to make requests to internal services, potentially exposing sensitive data or bypassing network restrictions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-54734?
CVE-2026-54734 is a critical server-side request forgery vulnerability in prebid-server-java, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Prebid Server Java is the Java version of Prebid Server. Prior to 3.43.0, certain bidder adapters interpolate user-supplied parameters into outbound request URLs without using HttpUtil to validate the resulting domain or path segment. A malicious actor who can supply bid-request parameters can cause the server to send HTTP requests to unintended destinations, potentially reaching internal network services, metadata endpoints, or other sensitive server endpoints with the server's network access. This issue is fixed in version 3.43.0.
Weakness: CWE-918
Which versions are affected by CVE-2026-54734?
How do I fix CVE-2026-54734?
No fix has been published for CVE-2026-54734 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-54734 being exploited?
There is no known exploitation of CVE-2026-54734 in the wild and no public exploit code.
Sources
Also known as GHSA-fr2c-g2f8-qchg.