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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-104890
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-05 16:17:06 UTC
Updated2026-10-06 16:08:43 UTC
DescriptionKunstmaan 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.

Risk And Classification

Primary CVSS: v3.1 7.2 HIGH from [email protected]

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

EPSS: 0.004160000 probability, percentile 0.337300000 (date 2026-10-06)

Problem Types: CWE-434 | CWE-434 CWE-434: Unrestricted Upload of File with Dangerous Type

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.2HIGHCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.2HIGHCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Kunstmaan KunstmaanBundlesCMS affected < 7.3.1 Not specified
CNA Kunstmaan Bundles-cms affected < 7.3.1 Not specified
CNA Kunstmaan Media-bundle affected < 7.3.1 Not specified

References

ReferenceSourceLinkTags
github.com/Kunstmaan/KunstmaanBundlesCMS/releases/tag/7.3.2 [email protected] github.com
github.com/Kunstmaan/KunstmaanBundlesCMS/security/advisories/GHSA-p279-5... [email protected] github.com
github.com/Kunstmaan/KunstmaanBundlesCMS/commit/1bbdfdeac8e7e91506b1a927... [email protected] github.com
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