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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是Grav组织开源的一款基于文件的扁平化内容管理系统。 Grav 3.9.2之前版本存在授权问题漏洞，该漏洞源于在sendInvitationEmail()函数中构造带令牌的邀请链接时未验证不可信的Host标头，可能导致攻击者操纵Host标头污染邀请链接并将用户重定向到攻击者控制的域。

CVSS 7.5 · High EPSS 0.43% · P36

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
Vulnerability Title
Grav 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Grav是Grav组织开源的一款基于文件的扁平化内容管理系统。 Grav 3.9.2之前版本存在授权问题漏洞，该漏洞源于在sendInvitationEmail()函数中构造带令牌的邀请链接时未验证不可信的Host标头，可能导致攻击者操纵Host标头污染邀请链接并将用户重定向到攻击者控制的域。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

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
AI-Generated POC Premium
Qwen3.6-35B-A3B · 8543 chars
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
100+ AI POC generations per month

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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