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 :
Aug. 24, 2026, 6:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-76838
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| 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.
-
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