CVE-2026-21861Public exploitNetwork attack vector

Authenticated RCE via unescaped updater parameter

Published Mar 31, 2026 · Updated Mar 31, 2026

OS command injection in baserCMS before 5.2.3 allows remote authenticated users to execute arbitrary commands through the core updater. PluginsController::get_core_update passes the POST php value to PluginsService::getCoreUpdate, which concatenates it into a shell command and calls exec() without validation or escaping. A valid administrator session and request token are required, and successful commands run with the web server account's privileges, enabling server data access and modification.

CVSS severity9.1
Critical
EPSS probability2.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

OS command injection in baserCMS before 5.2.3 allows remote authenticated users to execute arbitrary commands through the core updater. PluginsController::get_core_update passes the POST php value to PluginsService::getCoreUpdate, which concatenates it into a shell command and calls exec() without validation or escaping. A valid administrator session and request token are required, and successful commands run with the web server account's privileges, enabling server data access and modification.

The record

CVE
CVE-2026-21861
Published
Mar 31, 2026
Updated
Mar 31, 2026
Vendor
baserCMS Users Community
Product
baserCMS
Classifications
CWE-78, T1059
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Mar 31, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 31, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 5.2.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

baserCMS Users Community · baserCMSversion=< 5.2.3

Published CVSS scores

9.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
7.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059Command and Scripting Interpreter

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo