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CVE-2026-104890

7.2 · HIGH

Kunstmaan CMS is an open source content management system based on the Symfony framework.

Published Oct 5, 2026CWE-434EPSS 0.42%

Overview

CVE-2026-104890 is a high-severity vulnerability. It was published on October 5, 2026 and has a CVSS 3.1 base score of 7.2 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.2, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/Kunstmaan/KunstmaanBundlesCMS/commit/1bbdfdeac8e7e91506b1a9271360b9b68d7690d3GitHubgithub.com/Kunstmaan/KunstmaanBundlesCMS/releases/tag/7.3.2GitHubgithub.com/Kunstmaan/KunstmaanBundlesCMS/security/advisories/GHSA-p279-5wcv-45vq

How CyberStrike helps

Frequently asked questions

What is CVE-2026-104890?

CVE-2026-104890 is a high-severity vulnerability. It was published on October 5, 2026 and has a CVSS 3.1 base score of 7.2 (HIGH).

How severe is CVE-2026-104890?

This vulnerability has a CVSS 3.1 base score of 7.2, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-104890?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-104890?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-104890 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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