CVE-2021-21355 Information

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 the lack of ensuring file extensions belong to configured allowed mime-types attackers can upload arbitrary data with arbitrary file extensions - however default fileDenyPattern successfully blocked files like .htaccess or malicious.php. Besides that UploadedFileReferenceConverter transforming uploaded files into proper FileReference domain model objects handles possible file uploads for other extensions as well - given those extensions use the Extbase MVC framework make use of FileReference items in their direct or inherited domain model definitions and did not implement their own type converter. In case this scenario applies UploadedFileReferenceConverter accepts any file mime-type and persists files in the default location. In any way uploaded files are placed in the default location /fileadmin/user_upload/ in most scenarios keeping the submitted filename - which allows attackers to directly reference files or even correctly guess filenames used by other individuals disclosing this information. No authentication is required to exploit this vulnerability. This is fixed in versions 8.7.40 9.5.25 10.4.14 11.1.1.

CVSS Vector

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

Reference

https://typo3.org/security/advisory/typo3-core-sa-2021-002 https://packagist.org/packages/typo3/cms-form https://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-2r6j-862c-m2v2

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

LOW

Availability Impact

HIGH

Base Score

LOW

Base Severity

8.6