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

Quick assessment

Affected
getgrav grav
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Grav 3.9.2 之前版本中的 sendInvitationEmail() 函数在处理生成带令牌邀请链接时，未对用户可控的 Host 头部信息进行验证。攻击者可利用此漏洞篡改 Host 头部，从而毒化邀请链接，将用户重定向至攻击者控制的域名。该漏洞绕过了仅适用于密码重置流程的 require_trusted_host 保护机制。

CVSS 7.5 · High EPSS 0.26% · P17

Possible ATT&CK Techniques 1 AI

T1133 · External Remote Services

Affected Version Matrix 2

VendorProduct Version RangeStatus
getgrav grav < 3.9.2 affected
3.9.2 unaffected
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I. Basic Information for CVE-2026-56709

Vulnerability Information
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Vulnerability Title
Grav before 3.9.2 Host Header Injection via sendInvitationEmail
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
不恰当地信任反向DNS
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
getgrav grav 0 ~ 3.9.2 -

II. Public POCs for CVE-2026-56709

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 8543 chars
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III. Intelligence Information for CVE-2026-56709

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Vendor Advisories for CVE-2026-56709 (2)

Same Patch Batch · getgrav · 2026-08-25 · 15 CVEs total

CVE-2026-56710 9.8 CRITICAL Grav Login Plugin before 1.0.16 Privilege Escalation via Unlock
CVE-2026-75574 8.8 HIGH Grav before 4.2.2 Remote Code Execution via Email Twig
CVE-2026-72696 8.4 HIGH Grav CMS before 2.0.16 Symlink Following via createLockFile
CVE-2026-72695 8.1 HIGH Grav before 2.0.16 Path Traversal via MediaUploadTrait deleteFile
CVE-2026-56707 7.7 HIGH Grav Flex Objects 1.4.0 through 1.4.7 Authorization Bypass via Shortcode
CVE-2026-72700 7.5 HIGH Grav before 3.9.1 Timing Attack via Non-Constant-Time Token Comparison
CVE-2026-76846 7.5 HIGH Grav before 2.0.16 Information Disclosure via Twig Sandbox
CVE-2026-72698 6.5 MEDIUM Grav CMS before 2.0.16 Information Disclosure via Twig Sandbox Bypass
CVE-2026-72697 6.5 MEDIUM Grav CMS before 2.0.16 Path Traversal via media_directory
CVE-2026-76839 6.5 MEDIUM Grav before 2.0.16 Information Disclosure via offsetGet
CVE-2026-72702 5.4 MEDIUM Grav CMS before 2.0.16 Origin Validation Bypass via Referer
CVE-2026-72699 5.3 MEDIUM Grav Login Plugin before 3.9.1 Email Enumeration via Registration
CVE-2026-56708 5.3 MEDIUM Grav API Plugin before 1.0.16 SSRF via DNS Rebinding
CVE-2026-72701 3.7 LOW Grav CMS before 2.0.16 Timing Attack via verifyNonce

IV. Related Vulnerabilities

Same product: grav
Same vendor: getgrav
Same weakness: CWE-350

V. Comments for CVE-2026-56709

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