CVE-2026-76838 Hi.Events before 1.11.1-beta Server-Side Request Forgery via Unvalidated Webhook Redirects
Attackers can exploit unvalidated webhook redirects to access internal services and read sensitive data via the webhook logs endpoint.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-76838?
CVE-2026-76838 is a high-severity server-side request forgery vulnerability in HiEventsDev Hi.Events, published on 24 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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's DNS record after registration reaches the same result because no resolution is repeated. The response is not discarded: WebhookResponseHandlerService stores the body on the webhook log and WebhookLogResource returns it from the webhook logs endpoint, so the requester reads what the internal service replied rather than inferring it. Both event and organizer webhooks share the rule and the dispatch path. Version 1.11.1-beta revalidates at dispatch, pins the validated address, checks every redirect hop, and decodes IPv6 transition addresses that previously bypassed the filter.
Weakness: CWE-918
Which versions are affected by CVE-2026-76838?
How do I fix CVE-2026-76838?
No fix has been published for CVE-2026-76838 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-76838 being exploited?
There is no known exploitation of CVE-2026-76838 in the wild and no public exploit code.
Sources
Also known as GHSA-j9wc-mrp3-532h.