TI-2021-18091 Aliases CVE-2021-41258 GHSA-cq58-r77c-5jjw

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

LOW 34CWE-79Published 2021-11-16 · Updated 2024-08-04

Key facts

Attack vector: Network
Privileges required: Low
User interaction: Required
Attack complexity: Low
Impact type: Cross-site scripting
Confidentiality · integrity · availability: High · High · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-79.

Summary

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.

Why it matters now

EPSS 0.00807 57th percentileScored 2026-11-07

Fix Fixed kirby (getkirby): 3.5.8getkirby/cms (Packagist): 3.5.8

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
getkirby	kirby	3.5.0 to before 3.5.8	3.5.8	Patch available	CNA
—	getkirby/cms (Packagist)	3.5.0 to before 3.5.8	3.5.8	Patch available	GHSA-cq58-r77c-5jjw

kirby Vendorgetkirby Affected 3.5.0 to before 3.5.8 Fixed in 3.5.8 Patch available CNA
getkirby/cms (Packagist) Vendor— Affected 3.5.0 to before 3.5.8 Fixed in 3.5.8 Patch available GHSA-cq58-r77c-5jjw

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:getkirby:kirby::::::::	3.5.0 – 3.5.7.1	Vulnerable	getkirby

cpe:2.3:a:getkirby:kirby:*:*:*:*:*:*:*:* Versions 3.5.0 – 3.5.7.1 Vulnerable ·getkirby

Remediation

Fix · CNA kirby (getkirby) Fixed in 3.5.8
Fix · GHSA-cq58-r77c-5jjw getkirby/cms (Packagist) Fixed in 3.5.8 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2021-41258
2026-10-03 Alias added: GHSA-cq58-r77c-5jjw

References

Patch 1

https://github.com/getkirby/kirby/pull/3510

Advisory 3

Other 1

https://github.com/getkirby/kirby

TI-2024-17440 An arbitrary file upload vulnerability in the Profile Image module of Kirby CMS v4.1.0… CVSS 3.1HIGH 8.8
TI-2024-17439 An HTML injection vulnerability exists in the Edit Content Layout module of Kirby CMS… CVSS 3.1HIGH 7.1
TI-2026-23396 Kirby CMS through 5.1.4 allows an authenticated user with 'Editor' permissions to cause a… CVSS 3.1MEDIUM 6.5
TI-2024-17441 A stored cross-site scripting (XSS) vulnerability in the Edit Content Layout module of… CVSS 3.1MEDIUM 6.1
TI-2018-10413 An issue was discovered in Kirby 2.5.12. CVSS 3.1MEDIUM 5.4
TI-2024-17438 Kirby CMS v4.1.0 was discovered to contain a reflected self-XSS vulnerability via the URL parameter. CVSS 3.1MEDIUM 4.7

See all 40 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences