CVE intelligence and bounded remediation

CVE-2025-12346 — A vulnerability was detected in MaxSite CMS up to 109

High CVSS 8.8

A vulnerability was detected in MaxSite CMS up to 109. This vulnerability affects unknown code of the file application/maxsite/admin/plugins/auto_post/uploads-require-maxsite.php of the component HTTP Header Handler. Performing manipulation of the argument X-Requested-FileName/X-Requested-FileUpDir results in unrestricted upload. Remote exploitation of the attack is possible. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Severity
High
CVSS
8.8 (3.1)
Published
2025-10-28
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-284, CWE-434

Affected products

  • max-3000 / maxsite_cms

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

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Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

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