CVE-2026-100718
Deferred Deferred - Pending Action

Email Sender Spoofing in Froxlor

Publication date: 2026-09-26

Last updated on: 2026-09-26

Assigner: VulnCheck

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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Meta Information

Published
2026-09-26
Last Modified
2026-09-26
Generated
2026-09-26
AI Q&A
2026-09-26
EPSS Evaluated
N/A
NVD
CVE-2026-100718
EUVD
EUVD-2026-87691

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
froxlor froxlor to 2.3.12 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-276 During installation, installed file permissions are set to allow anyone to modify those files.

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Executive Summary

Froxlor through 2.3.10 has a vulnerability where the EmailSender.add API command bypasses the mail.allow_external_domains policy. Even when administrators disable external allowed-sender domains, authenticated customers with API access can still register arbitrary external sender addresses for their mailboxes. This creates a bypass between UI settings and API behavior, allowing sender spoofing.

Detection Guidance

Check Froxlor version with 'froxlor --version' or inspect the web interface. Verify if mail.enable_allow_sender is enabled while mail.allow_external_domains is disabled. Review API logs for EmailSender.add requests with external domains.

Impact Analysis

An attacker with normal customer API access could exploit this to send emails with spoofed sender identities outside their domain. This enables phishing attacks or unauthorized use of sender addresses, undermining anti-spoofing policies and potentially damaging reputation or trust.

Compliance Impact

This vulnerability could impact compliance by enabling spoofed emails, which may violate integrity requirements in GDPR or HIPAA. Organizations using Froxlor versions before 2.3.12 risk non-compliance due to unauthorized sender authorization, potentially leading to data protection violations.

Mitigation Strategies

Upgrade Froxlor to version 2.3.12 or later immediately. Disable mail.enable_allow_sender if external sender domains are not required. Audit API access logs for unauthorized EmailSender.add operations.

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