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CVE-2026-46392 haxtheweb CVE debrief

CVE-2026-46392 is a HIGH severity vulnerability in HAX CMS PHP prior to version 26.0.0. The `saveFile` endpoint validates upload extensions case-insensitively and writes the filename to disk verbatim. However, the `.htaccess` rule that forces `Content-Disposition: attachment` on HTML files is case-sensitive. This allows an HTML file uploaded with an uppercase extension (`.HTML`, `.Html`, `.HTM`) to be served as `text/html` without the forced-download header, enabling the browser to render it inline and execute any embedded JavaScript in the HAXcms origin. This bypasses the mitigation shipped for [CVE-2026-22704]({resourceLinkAnnotations.cve-org}).

Vendor
haxtheweb
Product
haxcms-php
CVSS
HIGH 8.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-05
Original CVE updated
2026-06-05
Advisory published
2026-06-05
Advisory updated
2026-06-05

Who should care

Users of HAX CMS PHP prior to version 26.0.0 should upgrade to version 26.0.0 or later to mitigate this vulnerability.

Technical summary

The `saveFile` endpoint in HAX CMS PHP prior to version 26.0.0 has a case-insensitive validation for upload extensions but writes filenames to disk verbatim. The `.htaccess` rule enforcing `Content-Disposition: attachment` for HTML files is case-sensitive. This discrepancy allows HTML files with uppercase extensions to bypass the forced-download header, enabling inline rendering and potential JavaScript execution.

Defensive priority

HIGH

Recommended defensive actions

  • Upgrade HAX CMS PHP to version 26.0.0 or later.
  • Review and adjust file upload and serving configurations to ensure proper handling of file extensions and content types.

Evidence notes

CVE-2026-46392 has a CVSS score of 8.7 and is considered HIGH severity. It was published on {cve.publishedAt} and modified on {cve.modifiedAt}.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-46392 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-46392

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-46392 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-46392

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.