CVE-2026-77203 Groups <= 4.6.0 - Authenticated (Subscriber+) Privilege Escalation via 'groups_join' Shortcode
Authenticated subscribers can escalate privileges to Administrator by exploiting flawed authorization in the Groups plugin's shortcode handler.
- 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-2026-77203?
CVE-2026-77203 is a high-severity vulnerability in itthinx Groups – Memberships and Access Control, published on 26 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The Groups – Memberships and Access Control plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 4.6.0. This is due to the groups_join() function deriving group-join eligibility from the ambient post's author capabilities via the global $post->post_author rather than from the currently authenticated user's own capabilities, while simultaneously minting and returning a valid groups-join-data hash and WordPress nonce for the caller in the same response — eliminating all authorization barriers to self-enrollment. This makes it possible for authenticated attackers, with Subscriber-level access and above, to enroll themselves into any group including privileged groups carrying the groups_admin_groups capability, and to subsequently create and join a group containing every registered WordPress capability, effectively escalating their privileges to Administrator. Exploitation requires the attacker to supply an Administrator-authored post ID via the post_ID parameter of the authenticated wp_ajax_parse_media_shortcode handler in order to establish the privileged ambient post context used by the flawed authorization check.
Weakness: CWE-269
Which versions are affected by CVE-2026-77203?
How do I fix CVE-2026-77203?
No fix has been published for CVE-2026-77203 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-77203 being exploited?
There is no known exploitation of CVE-2026-77203 in the wild and no public exploit code.
Sources
Also known as GHSA-cm6x-39f7-w4rc.