# CVE-2026-77203 — itthinx Groups – Memberships and Access Control

> As of 2026-09-26, CVE-2026-77203 is a HIGH-severity vulnerability in itthinx Groups – Memberships and Access Control, CVSS v3.1 8.8, EPSS 0.3% (23.2th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-77203 as of 2026-09-26; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-26

## What is CVE-2026-77203?

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.

The record classifies CVE-2026-77203 under weakness class [CWE-269](https://intel.threadlinqs.com/cwe/CWE-269). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 9 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.8 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 23.2% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.3/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-26

## Is CVE-2026-77203 being exploited?

It currently carries a trending score of 35 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **itthinx**: Groups – Memberships and Access Control

## How to fix CVE-2026-77203

No vendor patch reference has been recorded for CVE-2026-77203 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-77203

No threat campaign in the Threadlinqs corpus currently references CVE-2026-77203, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-09-28. This product uses the NVD API but is not endorsed or certified by the NVD.

**Other references**

- [wordfence.com](https://www.wordfence.com/threat-intel/vulnerabilities/id/e86dddc9-c1d3-426b-8ec7-2e56dc3c2379?source=cve)
- [plugins.trac.wordpress.org](https://plugins.trac.wordpress.org/browser/groups/tags/4.5.0/lib/views/class-groups-shortcodes.php#L586)
- [plugins.trac.wordpress.org (class groups shortcodes)](https://plugins.trac.wordpress.org/browser/groups/tags/4.5.0/lib/views/class-groups-shortcodes.php#L624)
- [plugins.trac.wordpress.org (class groups shortcodes)](https://plugins.trac.wordpress.org/browser/groups/tags/4.5.0/lib/views/class-groups-shortcodes.php#L463)
- [plugins.trac.wordpress.org (class groups wordpress)](https://plugins.trac.wordpress.org/browser/groups/tags/4.5.0/lib/wp/class-groups-wordpress.php#L248)

_Showing 5 of 7 recorded references._

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-77203
Full detection coverage and IOCs for threats exploiting CVE-2026-77203 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp