Server-Side Request Forgery (SSRF) in October CMS - #VU149488
Published: September 14, 2026
Vulnerability identifier: #VU149488
CSH Severity: Low
CVSS v4: 1.8 [CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to perform server-side request forgery.
The vulnerability exists due to improper validation of IPv4-mapped IPv6 addresses in SystemClassesResizeImages::validateExternalImageHost() when processing external image URLs. A remote privileged user can supply an IPv4-mapped IPv6 URL to the image resizer to perform server-side request forgery.
User interaction is required to render a template that passes untrusted input to the |resize Twig filter or ResizeImages::resize() API.
Affected software
October CMS
Remediation
Install security update from vendor's website.
October CMS - update to 4.3.5