CVE-2026-40590

Description

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.

CVSS v3.1 Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

EPSS — Exploit Prediction

0.0003

Probability of exploitation

0.08%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-639 CWE-639

References

Other References

https://github.com/freescout-help-desk/freescout/commit/b3d7611e6e173ed8a5e525b791deb6b32cf1ce62 https://github.com/freescout-help-desk/freescout/releases/tag/1.8.214 https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-wjw4-8xg6-342m https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-wjw4-8xg6-342m

Frequently Asked Questions

What is CVE-2026-40590? +

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. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-40590? +

CVE-2026-40590 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0003, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-40590? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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