Craft CMS up to 4.16.18/5.8.22 gethostbyname server-side request forgery

Summaryinfo

A vulnerability was found in Craft CMS up to 4.16.18/5.8.22. It has been declared as critical. Affected is the function gethostbyname. Executing a manipulation can lead to server-side request forgery. This vulnerability is registered as CVE-2026-27129. It is possible to launch the attack remotely. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Craft CMS up to 4.16.18/5.8.22. This vulnerability affects the function gethostbyname. The manipulation with an unknown input leads to a server-side request forgery vulnerability. The CWE definition for the vulnerability is CWE-918. 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. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-27129 since 02/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available.

Upgrading to version 4.16.19 or 5.8.23 eliminates this vulnerability. Applying the patch 2825388b4f32fb1c9bd709027a1a1fd192d709a3 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Content Management System

Vendor

• Craft

Name

• CMS

Version

• 4.16.0
• 4.16.1
• 4.16.2
• 4.16.3
• 4.16.4
• 4.16.5
• 4.16.6
• 4.16.7
• 4.16.8
• 4.16.9
• 4.16.10
• 4.16.11
• 4.16.12
• 4.16.13
• 4.16.14
• 4.16.15
• 4.16.16
• 4.16.17
• 4.16.18
• 5.8.0
• 5.8.1
• 5.8.2
• 5.8.3
• 5.8.4
• 5.8.5
• 5.8.6
• 5.8.7
• 5.8.8
• 5.8.9
• 5.8.10
• 5.8.11
• 5.8.12
• 5.8.13
• 5.8.14
• 5.8.15
• 5.8.16
• 5.8.17
• 5.8.18
• 5.8.19
• 5.8.20
• 5.8.21
• 5.8.22

License

• free

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Once again VulDB remains the best source for vulnerability data.

Discussion