CVE-2026-27129: Craft CMS

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Craft is a content management system (CMS). In versions 4.5.0-RC1 through 4.16.18 and 5.0.0-RC1 through 5.8.22, the SSRF validation in Craft CMS’s GraphQL Asset mutation uses `gethostbyname()`, which only resolves IPv4 addresses. When a hostname has only AAAA (IPv6) records, the function returns the hostname string itself, causing the blocklist comparison to always fail and completely bypassing SSRF protection. This is a bypass of the security fix for CVE-2025-68437. Exploitation requires GraphQL schema permissions for editing assets in the `<VolumeName>` volume and creating assets in the `<VolumeName>` volume. These permissions may be granted to authenticated users with appropriate GraphQL schema access and/or Public Schema (if misconfigured with write permissions). Versions 4.16.19 and 5.8.23 patch the issue.

Affected products

• Craft CMS Craft CMS: from 3.5.0, before 4.16.19 (fixed in 4.16.19); from 5.0.1, before 5.8.23 (fixed in 5.8.23); version 5.0.0 only

Published 2026-02-24. Last modified 2026-06-17.