CVE-2026-45127 MyBB: ACP Mass Mail draft resend CSRF
Attackers can force admins to create duplicate mass mail drafts via CSRF in the MyBB Admin Control Panel.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-45127?
CVE-2026-45127 is a low-severity vulnerability in mybb, published on 18 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
MyBB is free and open source forum software. Prior to 1.8.40, the ACP Mass Mail module does not validate certain requests correctly, allowing same-site attackers to create draft entries from archived entries by embedding a specially crafted URL. The Resend route in Admin CP, Users & Groups, Mass Mail, Mass Mailing Archive duplicates archived mailing entries into new drafts with mybb_massemails.status set to 0 on GET requests without request forgery protection. The uniquely identifying implementation details include Users & Groups → Mass Mail → Mass Mailing Archive, mybb_massemails.status = 0, and admin/modules/user/mass_mail.php. This issue is fixed in version 1.8.40.
Weakness: CWE-352
Which versions are affected by CVE-2026-45127?
How do I fix CVE-2026-45127?
No fix has been published for CVE-2026-45127 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-45127 being exploited?
There is no known exploitation of CVE-2026-45127 in the wild and no public exploit code.
Sources
Also known as GHSA-xx78-g79m-qvgq.