CVE Tools
Home/Vulnerability/CVE-2026-40591

CVE-2026-40591

FreeScout: Improper Authorization in Phone Conversation Creation Enables Cross-Mailbox Hidden Customer Modification

Published: Apr 21, 2026Updated: Apr 21, 2026 Sources: CVE List NVD
NVD MITRE
7.1CVSS
HIGH

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:LI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:HIntegrity
High
A:NAvailability
None

Weaknesses

CWE-639

Affected Products

freescout
freescout-help-desk

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

MITRE ATT&CK

1 technique
Initial Access
View detailed technique mapping

References

https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-9ff4-mmhv-x6jp
github.com
https://github.com/freescout-help-desk/freescout/commit/83eea1ca47d97c6cdc90c501734bc2579b014a34
github.com
https://github.com/freescout-help-desk/freescout/releases/tag/1.8.214
github.com

Timeline

Published
Apr 21, 2026
Last Updated
Apr 21, 2026

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-40591 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
AI-powered analysis
Plain-language impact assessment and exploitation scenario
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows