CVE-2021-36548Public exploitNetwork attack vector

Authenticated code execution via PHP template editing

Published Oct 28, 2021 · Updated Aug 4, 2024

Remote code execution in Monstra 3.0.4 allows remote authenticated users to execute arbitrary commands through the theme editor. The Blog theme editor accepts attacker-supplied PHP in a template and saves it as server-executable content without restricting dangerous code. Access requires a valid control-panel session; loading the modified Blog page executes the planted PHP with the web server's privileges.

CVSS severity9.8
Critical
EPSS probability3.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Remote code execution in Monstra 3.0.4 allows remote authenticated users to execute arbitrary commands through the theme editor. The Blog theme editor accepts attacker-supplied PHP in a template and saves it as server-executable content without restricting dangerous code. Access requires a valid control-panel session; loading the modified Blog page executes the planted PHP with the web server's privileges.

The record

CVE
CVE-2021-36548
Published
Oct 28, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1505.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1505.003Server Software Component: Web Shell

Public exploit references

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

Technologies

Your stack

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Your stack

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