---
title: "CVE-2026-87929: MaxSite CMS - Authentication Bypass"
description: "MaxSite CMS through 109.6 contains a broken authentication caused by a hardcoded session encryption key in application/config/config.php, letting unauthenticated attackers forge administrator session cookies, exploit requires knowledge of the hardcoded key."
url: https://panop.io/threat-heartbeat/CVE-2026-87929/
---

# CVE-2026-87929 MaxSite CMS - Authentication Bypass

MaxSite CMS through 109.6 contains a broken authentication caused by a hardcoded session encryption key in application/config/config.php, letting unauthenticated attackers forge administrator session cookies, exploit requires knowledge of the hardcoded key.

CVSS base score 9.8 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.53% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-87929)

## Details

Type

Authentication Bypass

Impact

Broken Authentication

CVSS vector

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

Published

9 September 2026

Updated

15 October 2026

Weakness

[CWE-321](https://cwe.mitre.org/data/definitions/321.html)

## Vendor fix

Update to a version that removes the hardcoded session encryption key or change the key during installation.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-87929](https://nvd.nist.gov/vuln/detail/CVE-2026-87929)
- [https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/config/config.php#L230-L254](https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/config/config.php#L230-L254)
- [https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/maxsite/common/core/init.php#L70-L96](https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/maxsite/common/core/init.php#L70-L96)
- [https://www.vulncheck.com/advisories/maxsite-cms-through-109.6-authentication-bypass-via-hardcoded-encryption-key](https://www.vulncheck.com/advisories/maxsite-cms-through-109.6-authentication-bypass-via-hardcoded-encryption-key)
- [https://github.com/EviL0rd/maxsite-cve4/blob/main/2026.09.08-maxsite-cms-hardcoded-session-key-auth-bypass.md](https://github.com/EviL0rd/maxsite-cve4/blob/main/2026.09.08-maxsite-cms-hardcoded-session-key-auth-bypass.md)
- [https://github.com/maxsite/cms](https://github.com/maxsite/cms)

[← All CVEs](https://panop.io/threat-heartbeat/)

## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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