CVE-2026-101005: October CMS SSRF Protection ResizeImages.php validateExternalImageHost server-side request forgery

Severity: high (CVSS 7.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-28 · updated 2026-09-28
Weakness: CWE-918

Description

A vulnerability was detected in October CMS up to 4.3.4. This affects the function validateExternalImageHost of the file System/Classes/ResizeImages.php of the component SSRF Protection. The manipulation results in server-side request forgery. The attack may be launched remotely. The exploit is now public and may be used. Upgrading to version 4.3.5 is able to mitigate this issue. You should upgrade the affected component.

Affected products

October CMS: 4.3.0, 4.3.1, 4.3.2, 4.3.3, 4.3.4

References

https://github.com/0xGenesi/CVE/blob/main/October_CMS_SSRF_IPv6_Mapped_IPv4_Bypass.md
https://github.com/octobercms/october/releases/tag/v4.3.5
https://github.com/octobercms/october/security/advisories/GHSA-j2j7-7m99-6226
https://vuldb.com/cve/CVE-2026-101005
https://vuldb.com/submit/922294
https://vuldb.com/vuln/410875
https://vuldb.com/vuln/410875/cti
https://www.cybersecurity-help.cz/vdb/vulns/149488/

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