# CVE-2021-47735: CMSimple 5.4 Authenticated Remote Code Execution via Template Editing

> Authenticated attackers can inject malicious PHP code via template editing to achieve remote code execution on CMSimple installations.

- **Severity:** High 8.6 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Dec 2025
- **Updated:** 5 Mar 2026
- **Also known as:** GHSA-9q7q-6c8f-q8gh

## What is CVE-2021-47735?

CVE-2021-47735 is a high-severity code injection vulnerability in Cmsimple, published on 23 Dec 2025. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

CMSimple 5.4 contains an authenticated remote code execution vulnerability that allows logged-in attackers to inject malicious PHP code into template files. Attackers can exploit the template editing functionality by crafting a reverse shell payload and saving it through the template editing endpoint with a valid CSRF token.

Weakness: CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2021-47735?

It affects 1 product.


Products: Cmsimple Cmsimple.

## How do I fix CVE-2021-47735?

No fix has been published for CVE-2021-47735 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-47735 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-47735 exists.

## Other vulnerabilities in Cmsimple

- [CVE-2021-43741](https://insights.sbomify.com/CVE-2021-43741/): Path traversal in n/a (critical 9.8)
- [CVE-2024-57548](https://insights.sbomify.com/CVE-2024-57548/): Missing authorization in n/a (critical 9.1)
- [CVE-2021-47734](https://insights.sbomify.com/CVE-2021-47734/): CMSimple 5.4 Authenticated Local File Inclusion Remote Code Execution (high 8.6)
- [CVE-2024-58280](https://insights.sbomify.com/CVE-2024-58280/): CMSimple 5.15 Remote Command Execution via Extensions Configuration (high 8.6)
- [CVE-2024-57546](https://insights.sbomify.com/CVE-2024-57546/): Information disclosure in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-47735 and fix it if it is affected.

What it is: CVE-2021-47735 is a high-severity code injection vulnerability in Cmsimple, published on 23 Dec 2025. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-47735 exists.

Affected product: Cmsimple. 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-2021-47735/ (Markdown: https://insights.sbomify.com/CVE-2021-47735/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47735
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47735
- OSV: https://osv.dev/vulnerability/CVE-2021-47735

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47735/
Summaries are generated and may contain mistakes; the official description above is the record.