Log in Start free

Vulnerability · Published Oct 5, 2026 · Assigned by GitHub_M

CVE-2026-104890Kunstmaan CMS: MediaBundle extension blacklist bypass allows authenticated administrators to upload executable PHP files leading to remote code execution

High 7.2

In plain English

A high-severity unrestricted file upload in bundles-cms from kunstmaan. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.2High
Exploit odds (30 days)0.4%top 63.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Kunstmaan CMS is an open source content management system based on the Symfony framework. Prior to 7.3.2, src/Kunstmaan/MediaBundle/Helper/File/FileHandler.php performs the blacklisted_extensions check case-sensitively in FileHandler::getFilePath and lowercases the stored extension afterward. An authenticated backend user with media access can upload a mixed-case executable extension such as PHP that bypasses the check and is stored in the web-accessible media directory with an executable lowercase extension. The default blacklist also omits several server-executable extension types, allowing the same code-execution impact where the web server executes uploaded files. This issue is fixed in version 7.3.2.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Packagistkunstmaan/bundles-cms7.3.2GHSA-p279-5wcv-45vq
Packagistkunstmaan/media-bundle7.3.2GHSA-p279-5wcv-45vq

Affected products (as reported)

VendorProductVersions
Kunstmaan KunstmaanBundlesCMS < 7.3.1
kunstmaan bundles-cms < 7.3.1
kunstmaan media-bundle < 7.3.1

Weakness: CWE-434 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

References