CVE-2026-76838
Hi.Events before 1.11.1-beta Server-Side Request Forgery via Unvalidated Webhook Redirects
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.
INFO
Published Date :
Aug. 24, 2026, 6:17 p.m.
Last Modified :
Oct. 12, 2026, 3:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 4.0 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update the webhook server software.
- Configure Guzzle options to disable redirect following.
- Pin validated webhook addresses after registration.
- Check every redirect hop during dispatch.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-76838.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-76838 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-76838
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-76838 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-76838 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 12, 2026
Action Type Old Value New Value Added Translation Title: Hi.Events de HiEventsDev, Description: Hi.Events valida un destino de webhook solo cuyo se registra, nunca cuyo se usa. NoInternalUrlRule en backend/app/Validators/Rules/NoInternalUrlRule.php resuelve el nombre de host con gethostbyname() y rechaza rangos privados y reservados, lo que cualquier nombre de host público pasa. En el envío, WebhookDispatchService toma la URL almacenada y la llama a través de spatie/laravel-webhook-server sin repetir la verificación, y backend/config/webhook-server.php no establece opciones de Guzzle, por lo que el seguimiento de redirecciones permanece habilitado por defecto. Un destino que responde con una redirección a una dirección de loopback, privada o de metadatos en la nube, por lo tanto, hace que el servidor emita esa solicitud, y cambiar el registro DNS del nombre de host después del registro alcanza el mismo resultado porque no se repite ninguna resolución. La respuesta no se descarta: WebhookResponseHylerService almacena el cuerpo en el registro del webhook y WebhookLogResource lo devuelve desde el endpoint de registros de webhook, por lo que el solicitante lee lo que respondió el servicio interno en lugar de inferirlo. Tanto los webhooks de eventos como los de organizadores comparten la regla y la ruta de envío. La versión 1.11.1-beta revalida en el envío, fija la dirección validada, verifica cada salto de redirección y decodifica direcciones de transición IPv6 que previamente eludieron el filtro. -
CVE Modified by [email protected]
Aug. 27, 2026
Action Type Old Value New Value Added Reference https://github.com/HiEventsDev/Hi.Events Added Reference https://github.com/HiEventsDev/Hi.Events/blob/v.1.11.0-beta/backend/app/Validators/Rules/NoInternalUrlRule.php Added Reference https://github.com/HiEventsDev/Hi.Events/commit/cfbf468bb5b1 Added Reference https://github.com/HiEventsDev/Hi.Events/pull/1311 Added Reference https://www.vulncheck.com/advisories/hi-events-before-beta-server-side-request-forgery-via-unvalidated-webhook-redirects Removed Reference https://github.com/HiEventsDev/Hi.Events Removed Reference https://github.com/HiEventsDev/Hi.Events/blob/v.1.11.0-beta/backend/app/Validators/Rules/NoInternalUrlRule.php Removed Reference https://github.com/HiEventsDev/Hi.Events/commit/cfbf468bb5b1 Removed Reference https://github.com/HiEventsDev/Hi.Events/pull/1311 Removed Reference https://www.vulncheck.com/advisories/hi-events-before-beta-server-side-request-forgery-via-unvalidated-webhook-redirects -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 27, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-76838', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-27T13:54:31.294071Z'} -
New CVE Received by [email protected]
Aug. 24, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/HiEventsDev/Hi.Events', 'vendor': 'HiEventsDev', 'product': 'Hi.Events', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '1.11.1-beta', 'versionType': 'semver'}], 'packageURL': 'pkg:github/HiEventsDev/Hi.Events', 'defaultStatus': 'unaffected'}] Added 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N Added CWE CWE-918 Added Reference https://github.com/HiEventsDev/Hi.Events Added Reference https://github.com/HiEventsDev/Hi.Events/blob/v.1.11.0-beta/backend/app/Validators/Rules/NoInternalUrlRule.php Added Reference https://github.com/HiEventsDev/Hi.Events/commit/cfbf468bb5b1 Added Reference https://github.com/HiEventsDev/Hi.Events/pull/1311 Added Reference https://www.vulncheck.com/advisories/hi-events-before-beta-server-side-request-forgery-via-unvalidated-webhook-redirects