CVE-2026-75834
Grav before 2.0.14 Stored XSS via Invalid UTF-8 Byte
- State
- Published
- Severity
- 5.1 Medium
- Published
- Aug 18, 2026
- Updated
- Oct 8, 2026
- Reserved
- Aug 18, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.1 Medium | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N | VulnCheck |
| 3.1 | 5.4 Medium | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N | VulnCheck |
Weaknesses
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Products
| Product | Versions |
|---|---|
gravgetgrav |
|
References
- GitHub Security Advisory (GHSA-q2j8-x8hf-63ch)vendor-advisory
- VulnCheck Advisory: Grav before 2.0.14 Stored XSS via Invalid UTF-8 Bytethird-party-advisory
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