Incorrect Behavior Order: Validate Before Canonicalize in Kirby - #VU150659
Published: September 17, 2026
Vulnerability identifier: #VU150659
CSH Severity: Low
CVSS v4: 4.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-180
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to disclose sensitive information.
The vulnerability exists due to validate-before-canonicalize behavior in Dom::isAllowedUrl() when processing URLs in uploaded SVG files. A remote user can upload a crafted SVG file containing a reference to an attacker-controlled origin to disclose sensitive information.
The SVG must be rendered for the external reference to be fetched, which can expose the viewer\'s IP address, User-Agent, and request timing.
Affected software
Kirby
Remediation
Install security update from vendor's website.
Kirby - addressed in versions 4.9.6, 5.6.0