CVE-2026-56709Public exploitNetwork attack vector

Invitation-link poisoning via unvalidated Host header

Published Aug 25, 2026 · Updated Aug 26, 2026

Host header injection in the Grav Login Plugin before 3.9.2 allows remote authenticated users to poison token-bearing invitation links. In classes/Email.php, sendInvitationEmail() passes a relative token-bearing route to Utils::url(), which resolves it against the request-derived rootUrl() without the trusted-host guards used by other sensitive email flows. The sender must be authenticated and the site must lack a Site Host or Custom Base URL; following the poisoned link exposes its invitation token to an attacker-controlled domain.

CVSS severity8.7
High
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Host header injection in the Grav Login Plugin before 3.9.2 allows remote authenticated users to poison token-bearing invitation links. In classes/Email.php, sendInvitationEmail() passes a relative token-bearing route to Utils::url(), which resolves it against the request-derived rootUrl() without the trusted-host guards used by other sensitive email flows. The sender must be authenticated and the site must lack a Site Host or Custom Base URL; following the poisoned link exposes its invitation token to an attacker-controlled domain.

The record

CVE
CVE-2026-56709
Published
Aug 25, 2026
Updated
Aug 26, 2026
Vendor
GetGrav
Product
Grav
Classifications
CWE-350, T1566.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.9.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GetGrav · Gravversion=0 <3.9.2

Published CVSS scores

8.7VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-350Reliance on Reverse DNS Resolution for a Security-Critical Action
T1566.002Phishing: Spearphishing Link

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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