---
id: CVE-2026-56709
title: >-
  Grav before 3.9.2 fails to validate untrusted Host headers in the
  sendInvitationEmail() function when constructing token-bearing invitation
  links
summary: >-
  Grav before 3.9.2 fails to validate untrusted Host headers in the
  sendInvitationEmail() function when constructing token-bearing invitation
  links. Attackers can manipulate the Host header to poison invitation links and
  redirect users to …
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-350
published: '2026-08-25'
updated: '2026-10-12'
sourceUpdated: '2026-10-12T15:10:00.207'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-56709'
references:
  - url: 'https://github.com/getgrav/grav/security/advisories/GHSA-69vf-mjxw-x79j'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/grav-before-host-header-injection-via-sendinvitationemail
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.00434
epssPercentile: 0.35852
ingestedAt: '2026-10-12T15:55:08.146Z'
---

## Overview

Grav before 3.9.2 fails to validate untrusted Host headers in the sendInvitationEmail() function when constructing token-bearing invitation links. Attackers can manipulate the Host header to poison invitation links and redirect users to attacker-controlled domains, bypassing the require_trusted_host protection which only covers password reset flows.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.