---
title: "CVE-2026-87930: MaxSite CMS - Insecure Deserialization"
description: "MaxSite CMS through 109.6 contains an insecure deserialization vulnerability caused by passing the ci_session cookie to unserialize() without class restrictions, letting unauthenticated attackers inject PHP objects and potentially execute code."
url: https://panop.io/threat-heartbeat/CVE-2026-87930/
---

# CVE-2026-87930 MaxSite CMS - Insecure Deserialization

MaxSite CMS through 109.6 contains an insecure deserialization vulnerability caused by passing the ci\_session cookie to unserialize() without class restrictions, letting unauthenticated attackers inject PHP objects and potentially execute code.

CVSS base score 8.1 /10

High

CISA KEV

Not listed

Public exploit

Proof of concept available

Authentication

Not required

EPSS

0.61% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-87930)

## Details

Type

Insecure Deserialization

Impact

Remote Code Execution, Data Tampering

CVSS vector

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

Published

9 September 2026

Updated

15 October 2026

Weakness

[CWE-502](https://cwe.mitre.org/data/definitions/502.html)

## Vendor fix

Update to the latest version beyond 109.6.

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-2026-87930](https://nvd.nist.gov/vuln/detail/CVE-2026-87930)
- [https://www.vulncheck.com/advisories/maxsite-cms-through-109.6-php-object-injection-via-ci-session](https://www.vulncheck.com/advisories/maxsite-cms-through-109.6-php-object-injection-via-ci-session)
- [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/EviL0rd/maxsite-cve6/blob/main/2026.09.08-maxsite-cms-unsafe-unserialize-object-injection.md](https://github.com/EviL0rd/maxsite-cve6/blob/main/2026.09.08-maxsite-cms-unsafe-unserialize-object-injection.md)
- [https://github.com/maxsite/cms](https://github.com/maxsite/cms)
- [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/system/libraries/Session.php#L670-L680](https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/system/libraries/Session.php#L670-L680)
- [https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/system/libraries/Session.php#L740-L742](https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/system/libraries/Session.php#L740-L742)

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## 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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