---
title: "CVE-2026-78834: CMSimple - Remote Code Execution"
description: "CMSimple 5.22 contains a server-side code execution caused by crafted external or uploaded text content in the CoAuthors plugin content import feature, letting authenticated low-privileged users execute code on the server, exploit requires low-privileged user authentication with content modification rights."
url: https://panop.io/threat-heartbeat/CVE-2026-78834/
---

# CVE-2026-78834 CMSimple - Remote Code Execution

CMSimple 5.22 contains a server-side code execution caused by crafted external or uploaded text content in the CoAuthors plugin content import feature, letting authenticated low-privileged users execute code on the server, exploit requires low-privileged user authentication with content modification rights.

CVSS base score 8.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.67% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-78834)

## Details

Type

Remote Code Execution

Impact

Remote Code Execution

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Published

8 September 2026

Updated

15 October 2026

Weakness

[CWE-94](https://cwe.mitre.org/data/definitions/94.html)

## Vendor fix

Update to the latest version of CMSimple and CoAuthors plugin.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-78834](https://nvd.nist.gov/vuln/detail/CVE-2026-78834)
- [https://gist.github.com/AEQ3/574cb644306776a9ff1a0de30b085e62](https://gist.github.com/AEQ3/574cb644306776a9ff1a0de30b085e62)
- [https://github.com/AEQ3/CVE/issues/1](https://github.com/AEQ3/CVE/issues/1)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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