CVE-2026-83628 Missing authorization in Theme My Login
Authenticated subscribers can bypass registration policies to create unauthorized subsites and gain administrator privileges on those new sites.
- 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-2026-83628?
CVE-2026-83628 is a medium-severity missing authorization vulnerability in jfarthing84 Theme My Login, published on 5 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The Theme My Login plugin for WordPress is vulnerable to Missing Authorization in versions up to, and including, 7.1.15 on Multisite installations. This is due to the `tml_ms_signup_handler()` function's `gimmeanotherblog` branch failing to enforce the network's `active_signup` registration policy, checking only `is_user_logged_in()` while sibling branches such as `validate-blog-signup` apply the full policy gate. This makes it possible for authenticated attackers, with Subscriber-level access and above, to directly POST `stage=gimmeanotherblog` to Theme My Login's signup route, bypassing the configured registration policy entirely — even when it is set to `none` or `user` — which causes `wpmu_create_blog()` to execute with the attacker's user ID, after which WordPress core assigns the Administrator role on the newly created subsite via `add_user_to_blog()`. The privilege gain is scoped to the newly created subsite only; the attacker's account retains Subscriber-level access on the main site and does not obtain Super Admin or network-level capabilities such as `manage_network` or `manage_sites`.
Weakness: CWE-862
Which versions are affected by CVE-2026-83628?
How do I fix CVE-2026-83628?
No fix has been published for CVE-2026-83628 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-83628 being exploited?
There is no known exploitation of CVE-2026-83628 in the wild and no public exploit code.
Sources
Also known as GHSA-6vjm-3j93-7v9p.