CVE-2026-100718: Permission Flaw (CVSS 7.1)

Description

Froxlor through 2.3.10 does not enforce the mail.allow_external_domains policy in the EmailSender.add API command. When an administrator has enabled the allowed-sender feature but disabled external allowed-sender domains (mail.enable_allow_sender = 1, mail.allow_external_domains = 0), an authenticated customer with API access can still use EmailSender.add to register an arbitrary external sender address for their mailbox, which is stored despite the policy. This creates a bypass between the UI/administrator configuration and the API, and — where the generated mail configuration consumes the allowed-sender table — allows a customer to authorize sender identities outside their hosted domains, facilitating sender spoofing. Fixed in 2.3.12.

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CVSS v3.1 Score

7.1

HIGH

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

EPSS — Exploit Prediction

0.0019

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-276 Incorrect Default Permissions

References

Other References

https://github.com/froxlor/froxlor/security/advisories/GHSA-m9j6-9856-68xf https://www.vulncheck.com/advisories/froxlor-before-2.3.12-authentication-bypass-via-emailsender-add

Frequently Asked Questions

What is CVE-2026-100718? +

Froxlor through 2.3.10 does not enforce the mail.allow_external_domains policy in the EmailSender.add API command. When an administrator has enabled the allowed-sender feature but disabled external allowed-sender domains (mail.enable_allow_sender = 1, mail.allow_external_domains = 0), an authenticated customer with API access can still use EmailSender.add to register an arbitrary external sender address for their mailbox, which is stored despite the policy. This creates a bypass between the UI/administrator configuration and the API, and — where the generated mail configuration consumes the allowed-sender table — allows a customer to authorize sender identities outside their hosted domains, facilitating sender spoofing. Fixed in 2.3.12. It has a CVSS v3.1 base score of 7.1 (HIGH).

How severe is CVE-2026-100718? +

CVE-2026-100718 has a CVSS v3.1 score of 7.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0019, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-100718? +

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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