CVE-2026-72552
Description
A flaw was found in Dub. This server-side request forgery (SSRF) vulnerability allows an unauthenticated remote attacker to force the server to make HTTP requests to arbitrary internal or external hosts. This can be exploited via the metatags edge endpoint, which processes caller-supplied URLs without proper validation or authentication. Successful exploitation could lead to information disclosure, such as scanning internal services or exfiltrating data from cloud metadata endpoints.
Statement
A Server-Side Request Forgery (SSRF) flaw exists in Dub's metatags edge endpoint. An unauthenticated remote attacker can supply arbitrary HTTP/HTTPS URLs to the endpoint, which fetches caller-provided addresses without enforcing IP denylists, domain egress controls, or authentication requirements. Consequently, the server executes arbitrary outbound network requests on behalf of the attacker, enabling internal network port scanning and exposure of local metadata endpoints or internal web services, posing an Important impact to confidentiality.
Mitigation
Restrict outbound network connectivity from the application host to block requests targeting private IP ranges and cloud metadata endpoints (e.g., 169.254.169.254). Alternatively, block external traffic or enforce strict authentication for the `/api/metatags` edge endpoint at the reverse proxy or API gateway level.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
Integrity
Technical Impact: Execute Unauthorized Code or Commands
Access Control
Technical Impact: Bypass Protection Mechanism
By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
Frequently Asked Questions
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