Vulnerability 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 Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Typo3 | Typo3 | >= 8.0.0, < 8.7.40 |
Related Weaknesses (CWE)
References
- https://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-2r6j-862c-m2v2Third Party Advisory
- https://packagist.org/packages/typo3/cms-formRelease NotesThird Party Advisory
- https://typo3.org/security/advisory/typo3-core-sa-2021-002Vendor Advisory
- https://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-2r6j-862c-m2v2Third Party Advisory
- https://packagist.org/packages/typo3/cms-formRelease NotesThird Party Advisory
- https://typo3.org/security/advisory/typo3-core-sa-2021-002Vendor Advisory
FAQ
What is CVE-2021-21355?
CVE-2021-21355 is a vulnerability with a CVSS score of 8.6 (HIGH). 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...
How severe is CVE-2021-21355?
CVE-2021-21355 has been rated HIGH with a CVSS base score of 8.6/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-21355?
Check the references section above for vendor advisories and patch information. Affected products include: Typo3 Typo3.