// For flags

CVE-2021-41258

Cross-site scripting (XSS) from image block content in the site frontend

Severity Score

5.4
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

Kirby is an open source file structured CMS. In affected versions Kirby'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.

Kirby es un CMS estructurado de archivos de código abierto. En las versiones afectadas, el campo blocks de Kirby almacena datos estructurados para cada bloque. Estos datos son usados en los fragmentos de bloque para convertir los bloques a HTML para ser usados en sus plantillas. Recomendamos escapar los caracteres especiales de HTML para protegerse de los ataques de tipo cross-site scripting (XSS). Lamentablemente, el fragmento predeterminado para el bloque de imágenes no usaba nuestro ayudante de escape. Esto permitía incluir código HTML malicioso en los campos source, alt y link del bloque de imagen, que luego se mostraría en el frontend del sitio y se ejecutaría en los navegadores de los visitantes del sitio y de los usuarios registrados que estuvieran navegando por él. Los atacantes deben estar en su grupo de usuarios autenticados del Panel para poder explotar esta debilidad. Los usuarios que no hacen uso del campo blocks no están afectados. Este problema ha sido parcheado en la versión 3.5.8 de Kirby al escapar los caracteres HTML especiales en la salida del fragmento de bloque de imagen por defecto. Por favor, actualice a esta versión o a una posterior para corregir la vulnerabilidad

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Attack Vector
Network
Attack Complexity
High
Authentication
Single
Confidentiality
None
Integrity
Partial
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-09-15 CVE Reserved
  • 2021-11-16 CVE Published
  • 2023-06-09 EPSS Updated
  • 2024-08-04 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Getkirby
Search vendor "Getkirby"
 Kirby
Search vendor "Getkirby" for product "Kirby"
 >= 3.5.0 <= 3.5.7.1
Search vendor "Getkirby" for product "Kirby" and version " >= 3.5.0 <= 3.5.7.1"
-
Affected