# CVE-2021-47976: TextPattern CMS 4.9.0-dev Authenticated Remote Code Execution via Plugin Upload

> Authenticated attackers can upload malicious PHP files via the plugin upload feature to achieve remote code execution on Textpattern CMS.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA: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:** 16 May 2026
- **Updated:** 18 May 2026
- **Also known as:** GHSA-77f2-mm55-xvp4

## What is CVE-2021-47976?

CVE-2021-47976 is a high-severity vulnerability in TextPattern CMS, published on 16 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

TextPattern CMS 4.9.0-dev contains a remote code execution vulnerability that allows authenticated attackers to upload arbitrary PHP files by exploiting the plugin upload functionality. Attackers can authenticate, retrieve a CSRF token from the plugin event page, and upload malicious PHP files to the textpattern/tmp/ directory for code execution.

Weakness: CWE-352 (Cross-Site Request Forgery)

## Which versions are affected by CVE-2021-47976?


## How do I fix CVE-2021-47976?

No fix has been published for CVE-2021-47976 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-47976 being exploited?

There is no known exploitation of CVE-2021-47976 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-47976 and fix it if it is affected.

What it is: CVE-2021-47976 is a high-severity vulnerability in TextPattern CMS, published on 16 May 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-2021-47976 in the wild and no public exploit code.

Affected product: TextPattern CMS. 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-2021-47976/ (Markdown: https://insights.sbomify.com/CVE-2021-47976/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47976
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47976
- OSV: https://osv.dev/vulnerability/CVE-2021-47976

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47976/
Summaries are generated and may contain mistakes; the official description above is the record.