CVE-2026-87928: File Upload RCE (CVSS 5.4)

Description

MaxSite CMS versions 0.94 through 109.6 contain a cross-site scripting vulnerability in the admin_page upload handler that allows any logged-in user to upload HTML files. Attackers can upload HTML containing malicious scripts to the uploads/_pages/ directory, which executes in visitors' browsers when the file is accessed, enabling persistent stored cross-site scripting attacks.

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CVSS v3.1 Score

5.4

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0017

Probability of exploitation

0.07%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-434 Unrestricted Upload

References

Other References

https://github.com/EviL0rd/maxsite-cve2/blob/main/2026.09.08-maxsite-cms-arbitrary-file-write-stored-xss.md https://github.com/maxsite/cms https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/maxsite/admin/plugins/admin_page/uploads-require-maxsite.php#L1-L64 https://www.vulncheck.com/advisories/maxsite-cms-0.94-through-109.6-html-upload-xss-via-admin-page

Frequently Asked Questions

What is CVE-2026-87928? +

MaxSite CMS versions 0.94 through 109.6 contain a cross-site scripting vulnerability in the admin_page upload handler that allows any logged-in user to upload HTML files. Attackers can upload HTML containing malicious scripts to the uploads/_pages/ directory, which executes in visitors' browsers when the file is accessed, enabling persistent stored cross-site scripting attacks. It has a CVSS v3.1 base score of 5.4 (MEDIUM).

How severe is CVE-2026-87928? +

CVE-2026-87928 has a CVSS v3.1 score of 5.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0017, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-87928? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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