HAXCMS PHP has a File Upload Validation Bypass

published 2026-06-05 5 mo ago modified 2026-07-23 3 mo ago also EUVD-2026-34894

cvss: 8.7; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits: 0; none known

HAX CMS helps manage microsite universe with PHP or NodeJs backends. Starting in version 11.0.6 and prior to version 25.0.0, the file upload functionality in HAXCMS PHP only validates file extensions using a regex pattern without checking the actual file content or MIME type. This allows attackers to upload malicious files (e.g., PHP webshells) disguised as legitimate image files, potentially leading to remote code execution. Version 25.0.0 contains a fix for the issue.

Patch / fix

fixed in 1

haxtheweb haxcms-php 25.0.0

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 5 mo ago (2026-06-08)

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/haxtheweb/issues/security/advisories/GHSA-ffxv-9qv2-v2v8 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.7	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA	4.0	8.7	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

haxtheweb haxcms-php

Classification

Weakness

CWE-434 Unrestricted Upload of File with Dangerous Type

References

github.com /haxtheweb/issues/security/advisories/GHSA-ffxv-9qv2-v2v8
exploit

Sources

CVE List CVE-2026-46400
NVD CVE-2026-46400

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary