CVE-2026-56709: Reliance on Reverse DNS Resolution for a Security-Critical Action in getgrav grav
Description
Grav versions prior to 3.9.2 contain a vulnerability in the sendInvitationEmail() function where untrusted Host headers are not properly validated. This allows attackers to manipulate the Host header to create invitation links that redirect users to attacker-controlled domains. The require_trusted_host protection only applies to password reset flows and does not mitigate this issue for invitation links.
CVSS v4.0
Score 8.7high
Affected software
getgrav
grav
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-56709 affects Grav before version 3.9.2. The vulnerability arises because the sendInvitationEmail() function relies on reverse DNS resolution and fails to validate untrusted Host headers when constructing token-bearing invitation links. Attackers can exploit this by poisoning the Host header, resulting in invitation links that redirect users to malicious domains. The existing require_trusted_host protection mechanism does not cover invitation flows, leaving this attack vector open.
Potential Impact
An attacker can craft invitation emails with manipulated Host headers, causing recipients to receive links that redirect to attacker-controlled domains. This can lead to phishing or social engineering attacks by misleading users about the legitimacy of the invitation link. The vulnerability does not require authentication or user interaction beyond receiving the invitation email.
Mitigation Recommendations
No official fix or patch is currently confirmed for this vulnerability. Users should monitor the vendor advisory for updates. Until a patch is available, avoid using invitation email features or implement additional validation on Host headers in custom deployments to prevent header manipulation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-06-22T18:48:27.060Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a8cf57aacd9273b49842873
Added to database: 08/25/2026, 01:52:58 UTC
Last enriched: 09/10/2026, 07:52:39 UTC
Last updated: 10/07/2026, 18:48:21 UTC
Views: 43
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