CVE-2021-41258

Severity CVSS v4.0:

Pending analysis

Type:

CWE-79 Cross-Site Scripting (XSS)

Publication date:

16/11/2021

Last modified:

18/11/2021

Description

Kirby is an open source file structured CMS. In affected versions Kirby&#39;s blocks field stores structured data for each block. This data is then used in block snippets to convert the blocks to HTML for use in your templates. We recommend to escape HTML special characters to protect against cross-site scripting (XSS) attacks. The default snippet for the image block unfortunately did not use our escaping helper. This made it possible to include malicious HTML code in the source, alt and link fields of the image block, which would then be displayed on the site frontend and executed in the browsers of site visitors and logged in users who are browsing the site. Attackers must be in your group of authenticated Panel users in order to exploit this weakness. Users who do not make use of the blocks field are not affected. This issue has been patched in Kirby version 3.5.8 by escaping special HTML characters in the output from the default image block snippet. Please update to this or a later version to fix the vulnerability.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 5.40 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): Required
Scope (S): Changed
Confidentiality (C): Low
Integrity (I): Low
Availability (A): None

Base Score 3.x

5.40

Severity 3.x

MEDIUM

Vector 2.0

AV:N/AC:H/Au:S/C:N/I:P/A:N CVSS v2.0 Severity and Metrics:

Base Score: 2.10 LOW
Vector: AV:N/AC:H/Au:S/C:N/I:P/A:N

Attack Vector (AV): Network
Attack Complexity (AC): High
Authentication (Au): Single
Confidentiality (C): None
Integrity (I): Physical
Availability (A): None