---
id: CVE-2026-87930
title: >-
  MaxSite CMS through 109.6 passes the ci_session cookie to unserialize()
  without class restrictions, allowing unauthenticated attackers to inject PHP
  objects
summary: >-
  MaxSite CMS through 109.6 passes the ci_session cookie to unserialize()
  without class restrictions, allowing unauthenticated attackers to inject PHP
  objects. Attackers can forge valid session cookies using the hardcoded
  encryption key to…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-502
vendor: MaxSite
product: MaxSite CMS
affected:
  - cms >= 0.78 <= 109.6
published: '2026-09-09'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T20:14:00.420'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-87930'
references:
  - url: >-
      https://github.com/EviL0rd/maxsite-cve4/blob/main/2026.09.08-maxsite-cms-hardcoded-session-key-auth-bypass.md
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/EviL0rd/maxsite-cve6/blob/main/2026.09.08-maxsite-cms-unsafe-unserialize-object-injection.md
    label: disclosure@vulncheck.com
  - url: 'https://github.com/maxsite/cms'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/config/config.php#L230-L254
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/system/libraries/Session.php#L670-L680
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/system/libraries/Session.php#L740-L742
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/maxsite-cms-through-109.6-php-object-injection-via-ci-session
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-09T17:22:33.214701Z'
ingestedAt: '2026-09-10T19:17:40.053Z'
epss: 0.00606
epssPercentile: 0.46857
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/winrarzipsexploit/CVE-2026-87930'
  checkedAt: '2026-09-27T10:34:04.673Z'
---

## Overview

MaxSite CMS through 109.6 passes the ci_session cookie to unserialize() without class restrictions, allowing unauthenticated attackers to inject PHP objects. Attackers can forge valid session cookies using the hardcoded encryption key to trigger magic methods and corrupt application state or achieve code execution if gadget classes exist.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.