CVSS8.5
Severityhigh
WeaknessCWE-918
ExploitedNot in CISA KEV
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
Description
Hi.Events validates a webhook destination only when it is registered, never when it is used. NoInternalUrlRule in backend/app/Validators/Rules/NoInternalUrlRule.php resolves the hostname with gethostbyname() and rejects private and reserved ranges, which any public hostname passes. At dispatch, WebhookDispatchService takes the stored URL and calls it through spatie/laravel-webhook-server without repeating the check, and backend/config/webhook-server.php sets no Guzzle options, so redirect following remains enabled by default. A destination that answers with a redirect to a loopback, private or cloud metadata address therefore causes the server to issue that request, and changing the hostname