CVE-2026-41587Public exploitNetwork attack vector

Authenticated code execution via unrestricted theme files

Published May 7, 2026 · Updated May 7, 2026

Unrestricted file upload in CI4MS 0.26.0.0 through 0.31.6.0 allows remote authenticated users to execute PHP through a theme ZIP. The theme installer calls install_theme_from_tmp() and renames every archive file into public/templates without extension, MIME, or content checks. A backend account with theme-upload permission is required, after which the uploaded PHP runs as the web server process through an HTTP request.

CVSS severity8.6
High
EPSS probability0.50%
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

Unrestricted file upload in CI4MS 0.26.0.0 through 0.31.6.0 allows remote authenticated users to execute PHP through a theme ZIP. The theme installer calls install_theme_from_tmp() and renames every archive file into public/templates without extension, MIME, or content checks. A backend account with theme-upload permission is required, after which the uploaded PHP runs as the web server process through an HTTP request.

The record

CVE
CVE-2026-41587
Published
May 7, 2026
Updated
May 7, 2026
Vendor
Ci4MS
Product
CI4MS
Classifications
CWE-434, T1505.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 7, 2026CVE publishedPublication date reported by the CVE source.
  2. May 7, 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=>= 0.26.0.0, < 0.31.7.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Ci4MS · CI4MSversion=>= 0.26.0.0, < 0.31.7.0

Published CVSS scores

8.6GitHub, Inc.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

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

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