CVE-2026-100909 is a high-severity (CVSS 7.3) Server-Side Request Forgery (SSRF) vulnerability. No vendor fix is recorded yet; mitigation options are listed below.
A vulnerability was found in OctoberCMS up to 4.1.19/4.2.25/4.3.4. The impacted element is the function getSourcePathForResize of the file modules/system/classes/ResizeImages.php. The…
Description
A vulnerability was found in OctoberCMS up to 4.1.19/4.2.25/4.3.4. The impacted element is the function getSourcePathForResize of the file modules/system/classes/ResizeImages.php. The manipulation of the argument realSourcePath results in server-side request forgery. The attack may be performed from remote. The exploit has been made public and could be used. Upgrading to version 4.3.5 and 4.4.0 is sufficient to resolve this issue. The patch is identified as 0e9736aa2c6d6bd3d60ff6ef9e0b4d32ce387f58. The affected component should be upgraded.
Detection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2026-100909 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.
Frequently Asked Questions
Is CVE-2026-100909 in your dependencies?
Find it across , including transitive dependencies.