# CVE-2021-21355: Unrestricted File Upload in Form Framework > Attackers can upload arbitrary files to TYPO3 via the Form Framework, potentially leading to code execution or information disclosure without authentication. - **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 23 Mar 2021 - **Updated:** 3 Aug 2024 - **Also known as:** BIT-typo3-2021-21355, GHSA-2r6j-862c-m2v2 ## What is CVE-2021-21355? CVE-2021-21355 is a high-severity vulnerability in Typo3 Typo3, published on 23 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official 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. Weakness: CWE-552 (Files or Directories Accessible to External Parties), CWE-434 (Unrestricted Upload of File with Dangerous Type) ## Which versions are affected by CVE-2021-21355? 21 open source packages ship an affected version, including typo3/cms-form, typo3 and typo3/cms. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `typo3/cms-form` | Packagist | From 10.0.0 | 10.4.14 | | `typo3/cms-form` | Packagist | From 10.0.0 | 10.4.14 | | `typo3/cms-form` | Packagist | From 11.0.0 | 11.1.1 | | `typo3/cms-form` | Packagist | From 11.0.0 | 11.1.1 | | `typo3/cms-form` | Packagist | From 8.0.0 | 8.7.40 | | `typo3/cms-form` | Packagist | From 8.0.0 | 8.7.40 | | `typo3/cms-form` | Packagist | From 9.0.0 | 9.5.25 | | `typo3/cms-form` | Packagist | From 9.0.0 | 9.5.25 | | `typo3` | Bitnami | From 8.0.0 | 8.7.40, 9.5.25, 10.4.14, 11.1.1 | | `typo3/cms` | Packagist | From 10.0.0 | 10.4.14 | | `typo3/cms` | Packagist | From 10.0.0 | 10.4.14 | | `typo3/cms` | Packagist | From 11.0.0 | 11.1.1 | | `typo3/cms` | Packagist | From 11.0.0 | 11.1.1 | | `typo3/cms` | Packagist | From 9.0.0 | 9.5.25 | | `typo3/cms` | Packagist | From 9.0.0 | 9.5.25 | | `typo3/cms-core` | Packagist | From 10.0.0 | 10.4.14 | | `typo3/cms-core` | Packagist | From 10.0.0 | 10.4.14 | | `typo3/cms-core` | Packagist | From 11.0.0 | 11.1.1 | | `typo3/cms-core` | Packagist | From 11.0.0 | 11.1.1 | | `typo3/cms-core` | Packagist | From 9.0.0 | 9.5.25 | | `typo3/cms-core` | Packagist | From 9.0.0 | 9.5.25 | Products: Typo3 Typo3. ## How do I fix CVE-2021-21355? Upgrade typo3/cms-form to a fixed version for your release line: 10.4.14, 11.1.1, 8.7.40 or 9.5.25. ## Is CVE-2021-21355 being exploited? There is no known exploitation of CVE-2021-21355 in the wild and no public exploit code. ## Other vulnerabilities in Typo3 Typo3 - [CVE-2009-0258](https://insights.sbomify.com/CVE-2009-0258/): Indexed Search Engine for TYPO3 Command Execution via Metacharacter Injection (critical 10.0) - [CVE-2011-3583](https://insights.sbomify.com/CVE-2011-3583/): Typo3 SQL injection due to faulty prepared statements (critical 9.8) - [CVE-2011-4628](https://insights.sbomify.com/CVE-2011-4628/): Typo3 Authentication Bypass (critical 9.8) - [CVE-2023-24814](https://insights.sbomify.com/CVE-2023-24814/): Persisted Cross-Site Scripting in Frontend Rendering in typo3 (high 8.8) - [CVE-2021-41113](https://insights.sbomify.com/CVE-2021-41113/): Cross-Site-Request-Forgery in Backend URI Handling in Typo3 (high 8.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-21355 and fix it if it is affected. What it is: CVE-2021-21355 is a high-severity vulnerability in Typo3 Typo3, published on 23 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-21355 in the wild and no public exploit code. Affected packages and fixed versions: - typo3/cms-form (Packagist): affected from 10.0.0; fixed in 10.4.14 - typo3/cms-form (Packagist): affected from 10.0.0; fixed in 10.4.14 - typo3/cms-form (Packagist): affected from 11.0.0; fixed in 11.1.1 - typo3/cms-form (Packagist): affected from 11.0.0; fixed in 11.1.1 - typo3/cms-form (Packagist): affected from 8.0.0; fixed in 8.7.40 - typo3/cms-form (Packagist): affected from 8.0.0; fixed in 8.7.40 - typo3/cms-form (Packagist): affected from 9.0.0; fixed in 9.5.25 - typo3/cms-form (Packagist): affected from 9.0.0; fixed in 9.5.25 - typo3 (Bitnami): affected from 8.0.0; fixed in 8.7.40, 9.5.25, 10.4.14, 11.1.1 - typo3/cms (Packagist): affected from 10.0.0; fixed in 10.4.14 - typo3/cms (Packagist): affected from 10.0.0; fixed in 10.4.14 - typo3/cms (Packagist): affected from 11.0.0; fixed in 11.1.1 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-21355/ (Markdown: https://insights.sbomify.com/CVE-2021-21355/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21355 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21355 - OSV: https://osv.dev/vulnerability/CVE-2021-21355 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-21355/ Summaries are generated and may contain mistakes; the official description above is the record.