CVE-2026-40591 | freescout-help-desk freescout up to 1.8.213 Conversation customer_id/name/to_email/phone authorization (GHSA-9ff4-mmhv-x6jp)

VDB-358537 · CVE-2026-40591 · GHSA-9FF4-MMHV-X6JP FREESCOUT-HELP-DESK FREESCOUT UP TO 1.8.213 CONVERSATION CUSTOMER_ID/NAME/TO_EMAIL/PHONE AUTHORIZATION HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 6.5 $0-$5k 2.32+ Summaryinfo A vulnerability marked as critical has been reported in freescout-help-desk freescout up to 1.8.213. This vulnerability affects unknown code of the component Conversation Handler. This manipulation of the argument customer_id/name/to_email/phone causes authorization. This vulnerability is tracked as CVE-2026-40591. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component. Detailsinfo A vulnerability has been found in freescout-help-desk freescout up to 1.8.213 and classified as critical. Affected by this vulnerability is an unknown code of the component Conversation Handler. The manipulation of the argument customer_id/name/to_email/phone with an unknown input leads to a authorization vulnerability. The CWE definition for the vulnerability is CWE-639. The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is: 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. The advisory is shared at github.com. This vulnerability is known as CVE-2026-40591 since 04/14/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available. Upgrading to version 1.8.214 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 83eea1ca47d97c6cdc90c501734bc2579b014a34 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version. Productinfo Vendor freescout-help-desk Name freescout Version 1.8.213 License open-source Website Product: https://github.com/freescout-help-desk/freescout/ CPE 2.3info 🔒 CPE 2.2info 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 6.7 VulDB Meta Temp Score: 6.5 VulDB Base Score: 6.3 VulDB Temp Score: 6.0 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 7.1 CNA Vector (GitHub_M): 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Authorization CWE: CWE-639 / CWE-285 / CWE-266 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: freescout 1.8.214 Patch: 83eea1ca47d97c6cdc90c501734bc2579b014a34 Timelineinfo 04/14/2026 CVE reserved 04/21/2026 +7 days Advisory disclosed 04/21/2026 +0 days VulDB entry created 04/21/2026 +0 days VulDB entry last update Sourcesinfo Product: github.com Advisory: GHSA-9ff4-mmhv-x6jp Status: Confirmed CVE: CVE-2026-40591 (🔒) GCVE (CVE): GCVE-0-2026-40591 GCVE (VulDB): GCVE-100-358537 Entryinfo Created: 04/21/2026 19:44 Changes: 04/21/2026 19:44 (69) Complete: 🔍 Cache ID: 99:887:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸