CVE-2026-71851 — crypto-js is a JavaScript library of crypto standards.¶
Key facts
CVE-2026-71851 is a Critical (9.0) vulnerability: crypto-js is a JavaScript library of crypto standards.. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-71851 |
| Severity | Critical (9.0) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-71851/ |
Details¶
English | 한국어
Description¶
crypto-js is a JavaScript library of crypto standards. Versions of crypto-js prior to 4.0.0 generate randomness in CryptoJS.lib.WordArray.random() using a custom variation of the Multiply-With-Carry pseudorandom number generator, seeded from Math.random(), instead of a cryptographically secure source. This generator was introduced in version 3.1.2-4 and remained present in nearly every 3.x release. Nominal requests for 128 or 256 bits of entropy through this function produce effective search spaces of approximately 2 to the 39th and 2 to the 47th possibilities, small enough to enumerate on commodity hardware. Downstream wallet applications that used CryptoJS.lib.WordArray.random() as the entropy source for BIP39 recovery phrases are affected, and an attacker who enumerates the reduced output space can recover the resulting private keys and control the associated funds. This issue is fixed in version 4.0.0.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-71851 |
| Type | RCE |
| CVSS Score | 9.0 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-71851/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-2026-71851
# 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/brix/crypto-js/commit/b405ff597fb3ac76a7bdfbc72dca10ba1079b1d5
- https://github.com/brix/crypto-js/security/advisories/GHSA-rg76-677x-56q9
- https://www.coinspect.com/blog/ill-bloom-investigation
Generated by PoC Generator on 2026-08-08T05:40:04.931898468
Frequently asked questions¶
What is CVE-2026-71851?¶
CVE-2026-71851 is a Critical (9.0) vulnerability: crypto-js is a JavaScript library of crypto standards.. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-71851?¶
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-2026-71851?¶
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.