CVE-2026-54734: SSRF (CVSS 10)

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.

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CVSS v3.1 Score

10.0

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0062

Probability of exploitation

0.49%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-918 Server-Side Request Forgery (SSRF)

References

Other References

https://github.com/prebid/prebid-server-java/commit/a129a685b6fc54441c1a779ce29ea4ec20c2e09f https://github.com/prebid/prebid-server-java/commit/d0c723ce36aa09712c825ea9625d978f45d29a1c https://github.com/prebid/prebid-server-java/pull/4522 https://github.com/prebid/prebid-server-java/releases/tag/3.43.0 https://github.com/prebid/prebid-server-java/security/advisories/GHSA-fr2c-g2f8-qchg

Frequently Asked Questions

What is CVE-2026-54734? +

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. It has a CVSS v3.1 base score of 10.0 (CRITICAL).

How severe is CVE-2026-54734? +

CVE-2026-54734 has a CVSS v3.1 score of 10.0 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0062, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-54734? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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