CVE-2026-100718 Froxlor before 2.3.12 Authentication Bypass via EmailSender.add
Authenticated customers can bypass external sender restrictions via API to register arbitrary sender addresses, enabling sender spoofing.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-100718?
CVE-2026-100718 is a high-severity authentication bypass vulnerability in froxlor, published on 26 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-276
Which versions are affected by CVE-2026-100718?
How do I fix CVE-2026-100718?
No fix has been published for CVE-2026-100718 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-100718 being exploited?
There is no known exploitation of CVE-2026-100718 in the wild and no public exploit code.
Sources
Also known as GHSA-m5mc-84wm-h4mw, GHSA-m9j6-9856-68xf.