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Self cross-site scripting (self-XSS) in the URL field

Moderate
bastianallgeier published GHSA-57f2-8p89-66x6 Feb 26, 2024

Package

composer getkirby/cms (Composer)

Affected versions

<=3.6.6.4, 3.7.0-3.7.5.3, 3.8.0-3.8.4.2, 3.9.0-3.9.8, 3.10.0, 4.0.0-4.1.0

Patched versions

3.6.6.5, 3.7.5.4, 3.8.4.3, 3.9.8.1, 3.10.0.1, 4.1.1

Description

TL;DR

This vulnerability affects Kirby sites that use the URL field in any blueprint.

A successful attack commonly requires knowledge of the content structure by the attacker as well as social engineering of a user with access to the Panel. The attack cannot be automated.

The vulnerability is also limited to self-XSS and cannot directly affect other users or visitors of the site.


Introduction

Cross-site scripting (XSS) is a type of vulnerability that allows to execute any kind of JavaScript code inside the Panel session of the same or other users. In the Panel, a harmful script can for example trigger requests to Kirby's API with the permissions of the victim.

Self cross-site scripting (self-XSS, also called reflected XSS) typically involves a user inadvertently executing malicious code within their own context, often through social engineering techniques. This can occur when a user is tricked into pasting and executing malicious JavaScript code into the browser's developer console, address bar or form fields.

Such vulnerabilities are critical as they allow attackers to gain access to the system or to escalate their privileges if they get access to the Panel session of an admin user. Depending on your site, other JavaScript-powered attacks are possible.

Impact

The URL field allows users to open the entered link in a new tab by clicking the link icon inside the field. This can be used to quickly verify whether the entered URL is functional and correct.

In affected versions, Kirby copied the entered URL into the link target of that link button without validating or sanitizing the link. This could be abused by attackers with a javascript: URL that would then be executed in the user's context when the link button was clicked with Ctrl+Click/Cmd+Click.

Patches

The problem has been patched in Kirby 3.6.6.5, Kirby 3.7.5.4, Kirby 3.8.4.3, Kirby 3.9.8.1, Kirby 3.10.0.1, and Kirby 4.1.1. Please update to one of these or a later version to fix the vulnerability.

In all of the mentioned releases, we have changed the URL field to only make the link button clickable if the entered URL is valid and safe.

Credits

Thanks to Natwara Archeepsamooth (@PlyNatwara) for responsibly reporting the identified issue.

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
High
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
Low
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:H/PR:N/UI:R/S:U/C:L/I:L/A:N

CVE ID

CVE-2024-26481

Weaknesses

Credits