CVE-2026-56100 — SpringBlade versions from 2.7.3 up to but not including 5.0.0 contain a privilege…¶
Key facts
CVE-2026-56100 is a High (8.1) vulnerability: SpringBlade versions from 2.7.3 up to but not including 5.0.0 contain a privilege…. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-56100 |
| Severity | High (8.1) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-56100/ |
Details¶
English | 한국어
Description¶
SpringBlade versions from 2.7.3 up to but not including 5.0.0 contain a privilege escalation vulnerability that allows authenticated attackers to create system administrator accounts by sending crafted POST requests to an unprotected internal Feign user-creation endpoint exposed via @RestController without authorization checks. Attackers can exploit the gateway's authentication filter, which only validates JWT parsing without verifying user roles or caller identity, and leverage a hardcoded JWT signing key embedded in publicly available JARs to forge tokens and escalate privileges from a low-privilege user to administrator, enabling cross-tenant data pollution and persistent backdoor access.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-56100 |
| CVSS Score | 8.1 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-56100/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-2026-56100
# 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://gist.github.com/sud0why/e73405057dd7414a8c221ef17e0d0059#file-cve-2026-56100-springblade-authbypass-en-md
- https://github.com/chillzhuang/SpringBlade
- https://github.com/chillzhuang/SpringBlade/commit/c69b9547c942c697da2f3ee6a9265b6004abd645
- https://github.com/chillzhuang/SpringBlade/releases#release-v5.0.0
- https://www.vulncheck.com/advisories/springblade-privilege-escalation-via-exposed-feign-endpoint
Generated by PoC Generator on 2026-08-29T22:07:28.795530821
Frequently asked questions¶
What is CVE-2026-56100?¶
CVE-2026-56100 is a High (8.1) vulnerability: SpringBlade versions from 2.7.3 up to but not including 5.0.0 contain a privilege…. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-56100?¶
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-2026-56100?¶
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.