CVE-2026-56709

Grav before 3.9.2 Host Header Injection via sendInvitationEmail

HIGH
7.5
CVSS Score
Published: August 25, 2026 at 01:30 AM UTC
Updated: October 12, 2026 at 03:10 PM UTC
1 product affected across 1 vendorGrav

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Severity
HIGH7.5
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

90%
0 ≤ v < 3.9.20
Vendor states this is fixed in 3.9.2 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-350

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