CVE-2026-40590: FreeScout's Customer AJAX Create Modifies Hidden Existing Customer
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.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-40590?
CVE-2026-40590 has a moderate severity level due to the risk of modifying existing customers through the AJAX endpoint.
How do I fix CVE-2026-40590?
To fix CVE-2026-40590, upgrade FreeScout to version 1.8.214 or later.
What implications does CVE-2026-40590 have for user data?
CVE-2026-40590 may allow unauthorized modifications to existing customer data, potentially compromising user integrity.
Is CVE-2026-40590 present in version 1.8.214 and later of FreeScout?
No, CVE-2026-40590 is not present in versions 1.8.214 and later of FreeScout.
What product is affected by CVE-2026-40590?
CVE-2026-40590 affects the FreeScout help desk software prior to version 1.8.214.