# 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.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Sep 2026
- **Updated:** 26 Sep 2026
- **Also known as:** GHSA-cm6x-39f7-w4rc

## 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 (Improper Privilege Management)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77203 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-77203 in the wild and no public exploit code.

Affected product: itthinx Groups – Memberships and Access Control. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-77203/ (Markdown: https://insights.sbomify.com/CVE-2026-77203/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77203
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77203
- OSV: https://osv.dev/vulnerability/CVE-2026-77203

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-77203/
Summaries are generated and may contain mistakes; the official description above is the record.