Vulnerability Monitor

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CVE-2021-41258


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.


Security Impact Summary

This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.3, indicating it can be exploited remotely over the network with relatively low complexity though user interaction is required requiring only low-level privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), for affected systems. Impacting 1 product from getkirby organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2021-11-16T18:15:07.587

Last Modified

2024-11-21T06:25:54.383

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 7.3 (HIGH)

CVSSv2 Vector

AV:N/AC:H/Au:S/C:N/I:P/A:N

  • Access Vector: NETWORK
  • Access Complexity: HIGH
  • Authentication: SINGLE
  • Confidentiality Impact: NONE
  • Integrity Impact: PARTIAL
  • Availability Impact: NONE
Exploitability Score

3.9

Impact Score

2.9

Weaknesses
  • Type: Secondary
    CWE-79
  • Type: Primary
    CWE-79

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application getkirby kirby ≤ 3.5.7.1 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For getkirby's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.