CVE-2021-21357

Broken Access Control in Form Framework

HIGH
8.3
CVSS Score
Published: March 23, 2021 at 01:50 AM UTC
Updated: June 17, 2026 at 03:35 AM UTC
1 product affected across 1 vendorTYPO3

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Severity
HIGH8.3
Exploit prediction
EPSS 2%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

95%
v ≤ 10.4.13v ≤ 11.1.0v ≤ 8.7.39v ≤ 9.5.2410.0.0 ≤ v < 10.4.1411.0.0 ≤ v < 11.1.18.0.0 ≤ v < 8.7.409.0.0 ≤ v < 9.5.25
Affected range stops below 10.4.14, so it looks safe — our inference, not a vendor statement
Affected range stops below 11.1.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.7.40, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.5.25, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

CVSS

8.3HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-20CWE-22CWE-434

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