CVE-2026-54735

prebid-server's request forgery vulnerability allows for possible host environment data extraction

Workarounds

If one is unable to update, please make sure that the affected bidder adapters are disabled.

Certain bidder adapters accept user-supplied parameters that are interpolated into outbound request URLs. Without proper input validation, a malicious actor could craft bid request parameters that cause the server to send HTTP requests to unintended destinations, potentially exposing internal network services or sensitive server endpoints to unauthorized access.

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

CVE-2026-54735 has a CVSS score of 10.0 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.4.0); upgrading removes the vulnerable code path.

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Patched in v4.4.0

1. What is CVE-2026-54735? CVE-2026-54735 is a critical-severity server-side request forgery (SSRF) vulnerability in github.com/prebid/prebid-server/v4 (go), affecting versions < 4.4.0. It is fixed in 4.4.0. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is CVE-2026-54735? CVE-2026-54735 has a CVSS score of 10.0 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-54735?
   • github.com/prebid/prebid-server/v4 (go) (versions < 4.4.0)
   • github.com/prebid/prebid-server/v3 (go) (versions <= 3.30.0)
   • github.com/prebid/prebid-server/v2 (go) (versions <= 2.32.0)
   • github.com/prebid/prebid-server (go) (versions <= 0.275.0)
4. Is there a fix for CVE-2026-54735? Yes. CVE-2026-54735 is fixed in 4.4.0. Upgrade to this version or later.
5. Is CVE-2026-54735 exploitable, and should I be worried? Whether CVE-2026-54735 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-54735 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-54735? Upgrade github.com/prebid/prebid-server/v4 to 4.4.0 or later.