LinkAce is a self-hosted archive to collect website links. In versions 2.3.0 and below, the htmlKeywordsFromUrl function in the FetchController class accepts user-provided URLs and makes HTTP requests to them without validating that the destination is not an internal or private network resource. This Server-Side Request Forgery (SSRF) vulnerability allows authenticated attackers to use the application server to perform port scanning and service discovery on internal networks. Practical impact is very limited because the function only extracts content from HTML meta keywords tags, which prevents meaningful data exfiltration from databases, APIs, or cloud metadata endpoints. This issue is fixed in version 2.4.0.
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.