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CVE-2026-77203 — The Groups – Memberships and Access Control plugin for WordPress is vulnerable to…

Key facts

CVE-2026-77203 is a High (8.8) vulnerability: The Groups – Memberships and Access Control plugin for WordPress is vulnerable to…. This entry ships a detection-only PoC and a Docker test lab.
CVE CVE-2026-77203
Severity High (8.8)
Detection / prevention —
PoC poc.py
Source 2026/CVE-2026-77203/

Details

English | 한국어

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.

Vulnerability Details

Property Value
CVE ID CVE-2026-77203
CVSS Score 8.8

Proof of Concept

Download

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-77203/poc.py

Usage

# Run PoC against target
python3 poc.py --target <TARGET_URL>

# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>

⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.

Test Lab

This repository includes a Docker-based test environment with both vulnerable and patched applications.

Quick Start

# Clone and navigate to CVE directory
cd CVE-2026-77203

# Start both applications
docker-compose up -d

# Run tests
./run-tests.sh    # Linux/Mac
./run-tests.ps1   # Windows PowerShell

Application Endpoints

Application URL Status
Vulnerable App http://localhost:8080 Shows vulnerability
Patched App http://localhost:8081 Demonstrates fix

Directory Structure

├── README.md           # English documentation
├── README_KO.md        # Korean documentation
├── poc.py              # PoC detection script
├── docker-compose.yml  # Container orchestration
├── run-tests.sh        # Linux/Mac test runner
├── run-tests.ps1       # Windows test runner
├── vulnerable-app/     # Vulnerable version
│   ├── app.py
│   ├── Dockerfile
│   └── requirements.txt
└── patched-app/        # Fixed version
    ├── app.py
    ├── Dockerfile
    └── requirements.txt

References

  • https://plugins.trac.wordpress.org/browser/groups/tags/4.5.0/lib/views/class-groups-shortcodes.php#L463
  • https://plugins.trac.wordpress.org/browser/groups/tags/4.5.0/lib/views/class-groups-shortcodes.php#L521
  • https://plugins.trac.wordpress.org/browser/groups/tags/4.5.0/lib/views/class-groups-shortcodes.php#L586
  • https://plugins.trac.wordpress.org/browser/groups/tags/4.5.0/lib/views/class-groups-shortcodes.php#L624
  • https://plugins.trac.wordpress.org/browser/groups/tags/4.5.0/lib/wp/class-groups-wordpress.php#L248
  • https://plugins.trac.wordpress.org/changeset/3693123/groups
  • https://www.wordfence.com/threat-intel/vulnerabilities/id/e86dddc9-c1d3-426b-8ec7-2e56dc3c2379?source=cve

Generated by PoC Generator on 2026-09-27T04:07:45.010815164

Frequently asked questions

What is CVE-2026-77203?

CVE-2026-77203 is a High (8.8) vulnerability: The Groups – Memberships and Access Control plugin for WordPress is vulnerable to…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-77203?

Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.

How do I block or mitigate CVE-2026-77203?

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

For authorized security testing and research only. See the full source and NVD record.