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Vulnerability record · CVE-2021-40940 · published 15 June 2022

CVE-2021-40940: Monstra unrestricted file upload vulnerability

Monstra · Monstra

Monstra 3.0.4 does not filter the case of php, which leads to an unrestricted file upload vulnerability.

9.8 CVSS 3.1 Critical EPSS 1.6% · top 24.7% CWE-434 · Unrestricted file upload
9.8CVSS 3.1 base score, v2 7.5
1.6%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

Monstra 3.0.4 does not filter the case of php, which leads to an unrestricted file upload vulnerability.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/monstra-cms/monstra/issues/471 ExploitIssue TrackingPatchThird Party Advisory
https://github.com/monstra-cms/monstra/issues/471 ExploitIssue TrackingPatchThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-36548Monstra unrestricted file upload vulnerabilityA remote code execution (RCE) vulnerability in the component /admin/index.php?id=themes&action=edit_template&filename=blog of Monstra v3.0.4 allows a…EPSS 3.3%9.8CVE-2020-25414Monstra inclusion from untrusted sphere vulnerabilityA local file inclusion vulnerability was discovered in the captcha function in Monstra 3.0.4 which allows remote attackers to execute arbitrary PHP c…EPSS 2.0%8.8CVE-2020-13384Monstra unrestricted file upload vulnerabilityMonstra CMS 3.0.4 allows remote authenticated users to upload and execute arbitrary PHP code via admin/index.php?id=filesmanager because, for example…EPSS 2.5%8.8CVE-2018-16608Monstra insecure direct object reference vulnerabilityIn Monstra CMS 3.0.4, an attacker with 'Editor' privileges can change the password of the administrator via an admin/index.php?id=users&action=edit&u…EPSS 1.2%8.8CVE-2018-9037Monstra unrestricted file upload vulnerabilityMonstra CMS 3.0.4 allows remote code execution via an upload_file request for a .zip file, which is automatically extracted and may contain .php file…EPSS 2.8%8.8CVE-2018-6383Monstra vulnerabilityMonstra CMS through 3.0.4 has an incomplete "forbidden types" list that excludes .php (and similar) file extensions but not the .pht or .phar extensi…EPSS 13%8.8CVE-2017-18048Monstra CMS case-sensitive extension check allows arbitrary file upload RCEMonstra CMS 3.0.4 blocks the lowercase .php extension on uploads but not the uppercase .PHP, so an authenticated user can upload a PHP file that the …EPSS 63%analysed8.0CVE-2018-11474Monstra vulnerabilityMonstra CMS 3.0.4 has a Session Management Issue in the Administrations Tab. A password change at admin/index.php?id=users&action=edit&user_id=1 does…EPSS 1.1%

Source: NIST National Vulnerability Database (record CVE-2021-40940), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.