CVE-2026-75834— Grav before 2.0.14 Stored XSS via Invalid UTF-8 Byte
Quick assessment
Affected
getgrav grav
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
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 2.0.14之前版本存在跨站脚本漏洞，该漏洞源于Security::detectXss()函数中的XSS检测模式使用PCRE /u修饰符，单个无效UTF-8字节导致preg_match()返回false，从而绕过保存时的XSS安全检查，可能导致经过身份验证的攻击者存储恶意JavaScript并在访问页面时执行。
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I. Basic Information for CVE-2026-75834
Vulnerability Information
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Vulnerability Title
Grav before 2.0.14 Stored XSS via Invalid UTF-8 Byte
Source: CVE Program / CVE List V5
Vulnerability Description
Grav before 2.0.14 contains a stored cross-site scripting vulnerability in the Security::detectXss() function (system/src/Grav/Common/Security.php). All XSS detection patterns use the PCRE /u (UTF-8) modifier, so a single invalid UTF-8 byte anywhere in page content causes preg_match() to return false for every pattern, silently bypassing the save-time XSS safety gate (Validation::checkSafety()). An authenticated attacker with page-edit permissions (without the security.xss_whitelist privilege) can store malicious JavaScript that executes in the browser of a visitor who views the affected page.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
Grav 跨站脚本漏洞
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 2.0.14之前版本存在跨站脚本漏洞，该漏洞源于Security::detectXss()函数中的XSS检测模式使用PCRE /u修饰符，单个无效UTF-8字节导致preg_match()返回false，从而绕过保存时的XSS安全检查，可能导致经过身份验证的攻击者存储恶意JavaScript并在访问页面时执行。
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
II. Public POCs for CVE-2026-75834
| # | POC Description | Source Link | Shenlong Link |
|---|
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Vendor Advisories for CVE-2026-75834 (2)
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🔗 Grav before 2.0.14 Stored XSS via Invalid UTF-8 Byte | Advisories | VulnCheck third-party-advisory
Same Patch Batch · getgrav · 2026-08-18 · 14 CVEs total
| CVE-2026-75837 | 9.1 CRITICAL | Grav before 2.0.14 Privilege Escalation via Group Access Field |
| CVE-2026-75836 | 8.8 HIGH | Grav API Plugin before 1.0.14 Missing Authorization |
| CVE-2026-75827 | 8.8 HIGH | Grav before 2.0.15 Arbitrary File Write via error_log |
| CVE-2026-75828 | 8.7 HIGH | Grav before 2.0.15 Stored XSS via detectXss() Quote Bypass |
| CVE-2026-75829 | 8.1 HIGH | grav-plugin-api before 1.0.15 Twig SSTI via translate endpoint |
| CVE-2026-75831 | 7.6 HIGH | Grav before 2.0.15 Stored XSS via audio/video source URL |
| CVE-2026-75830 | 7.1 HIGH | grav-plugin-api before 1.0.15 Path Traversal via batchCopy |
| CVE-2026-74907 | 5.9 MEDIUM | Grav before 2.0.15 Path Traversal via plugin-asset-map.php |
| CVE-2026-75107 | 5.4 MEDIUM | Grav Form Plugin before 9.1.19 Stored XSS via Field Properties |
| CVE-2026-74908 | 4.6 MEDIUM | Grav plugin-api before 1.0.15 Script Injection via SVG |
| CVE-2026-75832 | 4.3 MEDIUM | Grav API Plugin before 1.0.14 Authorization Bypass |
| CVE-2026-75835 | 4.3 MEDIUM | Grav API Plugin before 1.0.14 Missing Authorization |
| CVE-2026-75833 | 4.2 MEDIUM | Grav API Plugin Open Redirect via Backslash Bypass |
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V. Comments for CVE-2026-75834
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