CVE-2026-75916 — SiYuan through 3.7.3 contains a cross-site scripting vulnerability in the '(('…¶
Key facts
CVE-2026-75916 is a High (8.6) vulnerability: SiYuan through 3.7.3 contains a cross-site scripting vulnerability in the '(('…. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-75916 |
| Severity | High (8.6) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-75916/ |
Details¶
English | 한국어
Description¶
SiYuan through 3.7.3 contains a cross-site scripting vulnerability in the '((' block-reference autocomplete hint popup. In genHintItemHTML() (app/src/protyle/hint/extend.ts), a candidate block's name, alias, and memo fields are concatenated into the popup's HTML without escaping. An attacker who can set these metadata fields on a block can inject a self-firing payload (e.g. ) that executes automatically when a victim types '((' followed by a search term that surfaces the crafted block. Because SiYuan's Electron windows run with nodeIntegration enabled, contextIsolation disabled, and no CSP, the injected script gains require('child_process') access, allowing the XSS to escalate to arbitrary OS command execution.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-75916 |
| Type | XSS |
| CVSS Score | 8.6 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-75916/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-2026-75916
# 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/siyuan-note/siyuan/security/advisories/GHSA-5prr-vgxq-69g9
- https://www.vulncheck.com/advisories/siyuan-xss-to-rce-via-unescaped-block-metadata-in-hint-popup
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-5prr-vgxq-69g9
Generated by PoC Generator on 2026-08-24T21:52:45.357644408
Frequently asked questions¶
What is CVE-2026-75916?¶
CVE-2026-75916 is a High (8.6) vulnerability: SiYuan through 3.7.3 contains a cross-site scripting vulnerability in the '(('…. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-75916?¶
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-2026-75916?¶
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.