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CVE-2021-21357

8.3 · HIGH

TYPO3 is an open source PHP based web content management system.

Published Mar 23, 2021CWE-20EPSS 1.61%

Overview

CVE-2021-21357 is a high-severity vulnerability. It was published on March 23, 2021 and has a CVSS 3.1 base score of 8.3 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.3, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 8.7.40, 9.5.25, 10.4.14, 11.1.1 due to improper input validation, attackers can by-pass restrictions of predefined options and submit arbitrary data in the Form Designer backend module of the Form Framework. In the default configuration of the Form Framework this allows attackers to explicitly allow arbitrary mime-types for file uploads - however, default _fileDenyPattern_ successfully blocked files like _.htaccess_ or _malicious.php_. Besides that, attackers can persist those files in any writable directory of the corresponding TYPO3 installation. A valid backend user account with access to the form module is needed to exploit this vulnerability. This is fixed in versions 8.7.40, 9.5.25, 10.4.14, 11.1.1.

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/TYPO3/TYPO3.CMS/security/advisories/GHSA-3vg7-jw9m-pc3fRefpackagist.org/packages/typo3/cms-formReftypo3.org/security/advisory/typo3-core-sa-2021-003GitHubgithub.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-3vg7-jw9m-pc3fRefpackagist.org/packages/typo3/cms-formReftypo3.org/security/advisory/typo3-core-sa-2021-003

How CyberStrike helps

Frequently asked questions

What is CVE-2021-21357?

CVE-2021-21357 is a high-severity vulnerability. It was published on March 23, 2021 and has a CVSS 3.1 base score of 8.3 (HIGH).

How severe is CVE-2021-21357?

This vulnerability has a CVSS 3.1 base score of 8.3, 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-2021-21357?

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-2021-21357?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-21357 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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