Hugos security.http.urls allowlist is the only control on outbound fetches made by resources.GetRemote, and it inspects the URL text alone. CheckAllowedHTTPURL in config/security/securityConfig.go applies the configured pattern list and then re-checks a canonicalised form of an integer, hex or octal IPv4 host, but it never resolves the hostname and never inspects the address the HTTP client actually connects to. The client constructed in resources/resource_factories/create/create.go installs no dial-time hook, so no check occurs at connection time either. A hostname that resolves to a loopback, private or cloud-metadata address therefore satisfies the policy, and the response body is embedded in the generated site. An attacker who can supply a URL through content, for example a front-matter field or a CMS field, can make the build fetch an internal endpoint and publish the response in the static output, so the build artifact itself carries the data out.
Weakness
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.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Red Hat Hardened Images | RedHat | hugo-main-0.166.0-0.1.hum1 | * |
Related Attack Patterns
References
- https://github.com/gohugoio/hugo
- https://github.com/gohugoio/hugo/blob/v0.165.0/config/security/securityConfig.go
- https://github.com/gohugoio/hugo/blob/v0.165.0/resources/resource_factories/create/create.go
- https://www.vulncheck.com/advisories/hugo-through-server-side-request-forgery-via-security-http-urls-lacking-destination-address-validation