CVE-2026-76838: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-j9wc-mrp3-532h
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CVSS 8.5
CWE-918
Published
Advisory Summary

CVE-2026-76838 is a HIGH (CVSS 8.5) security vulnerability vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Software libraries in the Maven ecosystem. The weakness occurs when the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-76838 at a Glance

CVE Identifier CVE-2026-76838
GHSA Identifier GHSA-j9wc-mrp3-532h
Severity HIGH
CVSS v3.1 Base Score 8.5
CWE Classification CWE-918: Server-Side Request Forgery (SSRF)
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 8.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-76838

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-76838, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

References

NVD — CVE-2026-76838 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-76838
Software Source Repository REPOSITORY
https://github.com/HiEventsDev/Hi.Events/pull/1311
Security Fix Commit FIX COMMIT
https://github.com/HiEventsDev/Hi.Events/commit/cfbf468bb5b1
Software Source Repository REPOSITORY
https://github.com/HiEventsDev/Hi.Events
Software Source Repository REPOSITORY
https://github.com/HiEventsDev/Hi.Events/blob/v.1.11.0-beta/backend/app/Validators/Rules/NoInternalUrlRule.php
www.vulncheck.com/advisories/hi-event... WEB
https://www.vulncheck.com/advisories/hi-events-before-beta-server-side-request-forgery-via-unvalidated-webhook-redirects

Frequently Asked Questions

What is CVE-2026-76838?
CVE-2026-76838 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-918: Server-Side Request Forgery (SSRF).
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-76838?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-76838?
CVE-2026-76838 has a CVSS v3.1 base score of 8.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N.
What CWE is associated with CVE-2026-76838?
CVE-2026-76838 is classified under CWE-918: Server-Side Request Forgery (SSRF) (The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.).
How can I check Maven dependencies for CVE-2026-76838?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-j9wc-mrp3-532h",
  "modified" : "2026-08-24T18:31:58Z",
  "published" : "2026-08-24T18:31:58Z",
  "aliases" : [ "CVE-2026-76838" ],
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N"
  }, {
    "type" : "CVSS_V4",
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  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
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  }, {
    "type" : "WEB",
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  }, {
    "type" : "WEB",
    "url" : "https://github.com/HiEventsDev/Hi.Events/commit/cfbf468bb5b1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/HiEventsDev/Hi.Events"
  }, {
    "type" : "WEB",
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  }, {
    "type" : "WEB",
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  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-24T18:17:22Z"
  }
}