← Vulnerability feed

Vulnerability record · CVE-2026-87930 · published 9 September 2026

CVE-2026-87930: Deserialization of untrusted data vulnerability

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.

9.2 CVSS 4.0 Critical EPSS 0.61% · top 53.1% CWE-502 · Deserialization of untrusted data Deferred
9.2CVSS 4.0 base score
0.61%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
7References
9 Sep 2026Last modified by NVD

Description

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.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/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:

References

LinkTags
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/maxsite/cms
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#L740-L742
https://www.vulncheck.com/advisories/maxsite-cms-through-109.6-php-object-injection-via-ci-session

Track CVE-2026-87930 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-23758Ajax.NET Professional ajaxpro.2 untrusted deserialization RCEAll versions of the ajaxpro.2 package (Ajax.NET Professional) deserialize untrusted data and permit deserialization of arbitrary .NET classes. That l…KEVEPSS 83%analysed9.8CVE-2026-63077JetBrains TeamCity unauthenticated RCE via agent polling deserializationJetBrains TeamCity before 2026.1.3 and 2025.11.7 deserializes untrusted data received through the agent polling protocol, allowing unauthenticated re…KEVEPSS 9.8%analysed9.8CVE-2026-50522Microsoft SharePoint deserialization flaw allows remote code executionMicrosoft SharePoint Server deserializes untrusted data, letting an unauthorized attacker run code over the network. The flaw is remotely reachable w…KEVEPSS 3.0%analysed9.8CVE-2026-58644Microsoft SharePoint deserialization flaw allows remote code executionMicrosoft SharePoint Server deserializes untrusted data, letting an unauthenticated network attacker execute code. The flaw is rated CVSS 9.8 critica…KEVEPSS 16%analysed8.8CVE-2026-45659Microsoft SharePoint Server deserialization flaw enables remote code executionMicrosoft SharePoint Server deserializes untrusted data, letting an authenticated attacker run code over the network. The flaw is remotely reachable,…KEVEPSS 2.7%analysed9.3CVE-2026-12569PTC Windchill PDMlink and FlexPLM deserialization RCEPTC Windchill PDMlink and FlexPLM contain a deserialization of untrusted data flaw (also classified as improper input validation) that allows remote …KEVEPSS 46%analysed9.3CVE-2026-45247Mirasvit Full Page Cache Warmer for Magento 2 PHP object injection RCEMirasvit Full Page Cache Warmer for Magento 2 before 1.11.12 passes the CacheWarmer cookie to PHP's native unserialize() without restriction, allowin…KEVEPSS 2.1%analysed8.8CVE-2023-21529Microsoft Exchange Server deserialization flaw enables remote code executionCVE-2023-21529 is a deserialization of untrusted data vulnerability (CWE-502) in Microsoft Exchange Server that allows remote code execution. It carr…KEVEPSS 59%analysed

Source: NIST National Vulnerability Database (record CVE-2026-87930), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.