Arbitrary file upload in Haxtheweb Haxcms-Php

CVE-2026-46392

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (29.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 29.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-46392: held from 0.002 to 0.004.

EPSS over last 30 days · oldest: 0.002 · newest: 0.004 · change: +0.002

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-46392?
CVE-2026-46392 is a high-severity vulnerability in Haxtheweb Haxcms-Php, classified under Improper Handling of Case Sensitivity. CVSS score: 8.7/10. Published 2026-06-05.
How severe is CVE-2026-46392?
High severity. CVSS v3 base score is 8.7 out of 10.