SEPTEMBER 18, 2026
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Case File

CVE-2026-76838

HIGH · CVSS 8.5 EPSS 0.31% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-08-24 · Last synced 2026-09-18

CyberRota Analysis

AI-Generated

The vulnerability arises from the inadequate validation of webhook destinations in Hi.Events, allowing attackers to exploit this oversight by redirecting requests to internal or private addresses after initial registration. This can lead to exposure of sensitive internal service responses in webhook logs, potentially compromising confidential information. Organizations using this software, particularly those handling sensitive data or operating in regulated environments, should prioritize addressing this vulnerability to mitigate risks of data leakage and unauthorized access.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

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CVE
CVE-2026-76838
Severity
HIGH
CVSS
8.5
EPSS
0.31%

Original NVD 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.