Kirby: Cross-site scripting (XSS) from incomplete HTML/XML sanitization in `Dom::sanitize()`

published 2026-06-18 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-42687 , GHSA-wr9h-4r83-f4v6

cvss: 8.5; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 46%
public exploits: 0; none known

Kirby is an open-source content management system. Prior to 4.9.4 and 5.4.4, Kirby sites and plugins that use the writer or list fields or call Dom::sanitize(), Sane::sanitize(), Sane::Html::sanitize(), Sane::Svg::sanitize(), Sane::Xml::sanitize(), Sane::sanitizeFile(), or file sanitizeContents() with untrusted input allow malicious markup injected as children of an unknown HTML or XML tag to pass through Dom::sanitize() without being correctly sanitized, causing stored cross-site scripting. This issue is fixed in versions 4.9.4 and 5.4.4.

Patch / fix

fixed in 3 links 6

packagist getkirby/cms 4.9.4, 5.4.4
getkirby kirby 4.9.4, 5.4.4
getkirby panel 4.9.4, 5.4.4

github.com/getkirby/kirby@0f0437b commit
github.com/getkirby/kirby@7ad76cf commit
github.com/getkirby/kirby@9ec1873 commit
github.com/getkirby/kirby@bb2562e commit
github.com/getkirby/kirby/releases/tag/4.9.4 release
github.com/getkirby/kirby/releases/tag/5.4.4 release

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 4 mo ago (2026-07-09)

Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.5	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CNA	4.0	8.5	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem	package	affected	fixed in
packagist	getkirby/cms	<4.9.4 >=5.0.0-alpha.1, <5.4.4	4.9.4 5.4.4

Affected products

getkirby kirby

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation
CWE-87 Improper Neutralization of Alternate XSS Syntax

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary