CVE-2026-46392
HAX CMS PHP Has a Stored XSS via Case-Sensitivity Mismatch in HTML Upload Validation
HAX CMS helps manage microsite universe with PHP or NodeJs backends. Prior to version 26.0.0 of HAX CMS PHP, the saveFile endpoint validates upload extensions case-insensitively and writes the filename to disk verbatim, but the .htaccess rule that forces Content-Disposition: attachment on HTML files is case-sensitive. An HTML file uploaded with an uppercase extension (.HTML, .Html, .HTM) is still served as text/html but the forced-download header never applies, so the browser renders it inline and executes any embedded JavaScript in the HAXcms origin. This bypasses the mitigation shipped for CVE-2026-22704. Version 26.0.0 contains a fix.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
HAX CMS PHP Has a Stored XSS via Case-Sensitivity Mismatch in HTML Upload Validation
HAX CMS helps manage microsite universe with PHP or NodeJs backends. Prior to version 26.0.0 of HAX CMS PHP, the saveFile endpoint validates upload extensions case-insensitively and writes the filename to disk verbatim, but the .htaccess rule that forces Content-Disposition: attachment on HTML files is case-sensitive. An HTML file uploaded with an uppercase extension (.HTML, .Html, .HTM) is still served as text/html but the forced-download header never applies, so the browser renders it inline and executes any embedded JavaScript in the HAXcms origin. This bypasses the mitigation shipped for CVE-2026-22704. Version 26.0.0 contains a fix.
- Record
CVE-2026-46392- CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - Weakness
- CWE-178, CWE-434
- Updated
- 2026-11-02
EUVDEUVD-2026-34883
HAX CMS helps manage microsite universe with PHP or NodeJs backends. Prior to version 26.0.0 of HAX CMS PHP, the saveFile endpoint validates upload extensions case-insensitively and writes the filename to disk verbatim, but the .htaccess rule that forces Content-Disposition: attachment on HTML files is case-sensitive. An HTML file uploaded with an uppercase extension (.HTML, .Html, .HTM) is still served as text/html but the forced-download header never applies, so the browser renders it inline and executes any embedded JavaScript in the HAXcms origin. This bypasses the mitigation shipped for CVE-2026-22704. Version 26.0.0 contains a fix.
- Record
EUVD-2026-34883- CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - Updated
- 2026-11-02
NVD
HAX CMS helps manage microsite universe with PHP or NodeJs backends. Prior to version 26.0.0 of HAX CMS PHP, the saveFile endpoint validates upload extensions case-insensitively and writes the filename to disk verbatim, but the .htaccess rule that forces Content-Disposition: attachment on HTML files is case-sensitive. An HTML file uploaded with an uppercase extension (.HTML, .Html, .HTM) is still served as text/html but the forced-download header never applies, so the browser renders it inline and executes any embedded JavaScript in the HAXcms origin. This bypasses the mitigation shipped for CVE-2026-22704. Version 26.0.0 contains a fix.
- Record
CVE-2026-46392- CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - Weakness
- CWE-178, CWE-434
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-46392 is a high vulnerability (CVSS 8.7) in Haxtheweb Haxcms-php, published June 5, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.27%, the 19th percentile. No source names a fixed version.