CVE-2026-54734 — Prebid Server Java is the Java version of Prebid Server.¶
Key facts
CVE-2026-54734 is a Critical (10.0) vulnerability: Prebid Server Java is the Java version of Prebid Server.. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-54734 |
| Severity | Critical (10.0) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-54734/ |
Details¶
English | 한국어
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.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-54734 |
| Type | SSRF |
| CVSS Score | 10.0 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-54734/poc.py
Usage¶
# Run PoC against target
python3 poc.py --target <TARGET_URL>
# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>
⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.
Test Lab¶
This repository includes a Docker-based test environment with both vulnerable and patched applications.
Quick Start¶
# Clone and navigate to CVE directory
cd CVE-2026-54734
# Start both applications
docker-compose up -d
# Run tests
./run-tests.sh # Linux/Mac
./run-tests.ps1 # Windows PowerShell
Application Endpoints¶
| Application | URL | Status |
|---|---|---|
| Vulnerable App | http://localhost:8080 | Shows vulnerability |
| Patched App | http://localhost:8081 | Demonstrates fix |
Directory Structure¶
├── README.md # English documentation
├── README_KO.md # Korean documentation
├── poc.py # PoC detection script
├── docker-compose.yml # Container orchestration
├── run-tests.sh # Linux/Mac test runner
├── run-tests.ps1 # Windows test runner
├── vulnerable-app/ # Vulnerable version
│ ├── app.py
│ ├── Dockerfile
│ └── requirements.txt
└── patched-app/ # Fixed version
├── app.py
├── Dockerfile
└── requirements.txt
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
Generated by PoC Generator on 2026-09-18T08:04:37.375957128
Frequently asked questions¶
What is CVE-2026-54734?¶
CVE-2026-54734 is a Critical (10.0) vulnerability: Prebid Server Java is the Java version of Prebid Server.. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-54734?¶
Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.
How do I block or mitigate CVE-2026-54734?¶
Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.
For authorized security testing and research only. See the full source and NVD record.