Skip to content

FormField with square brackets in field name skips validation

Moderate severity GitHub Reviewed Published Mar 26, 2022 to the GitHub Advisory Database • Updated Feb 7, 2024

Package

composer silverstripe/framework (Composer)

Affected versions

>= 3.0.0, < 4.7.4

Patched versions

4.7.4

Description

FileField with array notation skips validation

The FileField class is commonly used for file upload in custom code on a Silverstripe website. This field is designed to be used with a single file upload.

PHP allows for submitting multiple values by adding square brackets to the field name. When this is done to a FileField, it will be coerced into allowing multiple files by using this notation. This is not a supported feature, though nothing is done to prevent this.

In this scenario, validation such as limiting allowed extensions is not applied, and the FileField->saveInto() behaviour is not triggered. If custom controller logic is used to process the file uploads, it might implicitly rely on validation to be provided by the Form system, which is not the case.

References

Published to the GitHub Advisory Database Mar 26, 2022
Reviewed Mar 26, 2022
Last updated Feb 7, 2024

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(52nd percentile)

Weaknesses

CVE ID

CVE-2020-26138

GHSA ID

GHSA-7mv4-4xpg-xq44

Source code

No known source code
Loading Checking history
See something to contribute? Suggest improvements for this vulnerability.