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 ↗

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

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

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