CVE-2026-56709: Grav before 3.9.2 Host Header Injection via sendInvitationEmail

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-25 · updated 2026-10-12
Weakness: CWE-350

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 products

getgrav grav: before 3.9.2 — fixed in 3.9.2

How to fix

Upgrade to a fixed version: getgrav grav 3.9.2. Check the vendor advisory for mitigations.

References

https://github.com/getgrav/grav/security/advisories/GHSA-69vf-mjxw-x79j
https://www.vulncheck.com/advisories/grav-before-host-header-injection-via-sendinvitationemail

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