# CVE-2026-88764: Simple Membership < 4.7.8 - Subscriber+ Membership Level Escalation via PayPal Standard subsc_ref

> Attackers can escalate membership privileges by manipulating PayPal payment notifications, bypassing intended access controls in the Simple Membership plugin.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N`)
- **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:** 13 Sep 2026
- **Updated:** 13 Sep 2026
- **Also known as:** GHSA-cmhf-4mfx-3gf7

## What is CVE-2026-88764?

CVE-2026-88764 is a medium-severity vulnerability in Unknown Simple Membership, published on 13 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The Simple Membership WordPress plugin before 4.7.8 does not validate that the membership level supplied in a PayPal payment notification matches the level configured for the paid payment button, allowing members to pay for a lower-priced membership while being granted a higher, more privileged membership level.

Weakness: CWE-269 (Improper Privilege Management)

## Which versions are affected by CVE-2026-88764?


## How do I fix CVE-2026-88764?

No fix has been published for CVE-2026-88764 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-88764 being exploited?

There is no known exploitation of CVE-2026-88764 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-88764 and fix it if it is affected.

What it is: CVE-2026-88764 is a medium-severity vulnerability in Unknown Simple Membership, published on 13 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-2026-88764 in the wild and no public exploit code.

Affected product: Unknown Simple Membership. 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-2026-88764/ (Markdown: https://insights.sbomify.com/CVE-2026-88764/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-88764
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-88764
- OSV: https://osv.dev/vulnerability/CVE-2026-88764

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-88764/
Summaries are generated and may contain mistakes; the official description above is the record.