CVE-2026-27129: craftcms cms Server-Side Request Forgery (SSRF)

Vulnerability summary

CVE-2026-27129 is a medium (CVSS 6.5) Server-Side Request Forgery (SSRF) vulnerability in craftcms cms. EPSS estimates a 0.43% chance of exploitation in the next 30 days, higher than 35.4% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 24-02-2026
   PublishedVulnerability first disclosed.
2. 28-02-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-918Server-Side Request Forgery (SSRF)The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.