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: Packagist: craftcms/cms
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 ([GHSA-x27p-wfqw-hfcc](https://github.com/craftcms/cms/security/advisories/GHSA-x27p-wfqw-hfcc)).
## Required Permissions
Exploitation requires GraphQL schema permissions for: - Edit assets in the `<VolumeName>` volume - Create assets in the `<VolumeName>` volume
These permissions may be granted to: - Authenticated users with appropriate GraphQL schema access - Public Schema (if misconfigured with write permissions)
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## Technical Details
### Root Cause
From PHP documentation: *"gethostbyname - Get the IPv4 address corresponding to a given Internet host name"*
When no IPv4 (A record) exists, `gethostbyname()` returns the hostname string unchanged.
### Bypass Mechanism
``` +-----------------------------------------------------------------------------+ | Step 1: Attacker provides URL | | http://fd00-ec2--254.sslip.io/latest/meta-data/ | +-----------------------------------------------------------------------------+ | Step 2: Validation calls gethostbyname('fd00-ec2--254.sslip.io') | | -> No A record exists…