CVE-2026-46696: October CMS: Safe Mode Sandbox Bypass via Session Store and Forwarded Builder Calls

A vulnerability was identified in the Twig sandbox security policy that allowed a chained bypass when cms.safe_mode is enabled. The Laravel session store was exposed to Twig with unrestricted method access, and raw SQL methods reachable through Eloquent’s __call forwarding were not blocked across the full builder chain. When combined, a backend user with CMS markup editing access could read arbitrary database values via raw SQL expressions and write to the backend authentication session key, forging a backend session as another existing user.

Scope of impact is narrow. Safe Mode is a niche feature, primarily used for demo installations and multi-tenant or shared-editor scenarios where untrusted users are deliberately granted access to the CMS markup editor. Standard production deployments do not enable Safe Mode, because under normal October CMS guidance backend access - including markup editing - is restricted to trusted administrators, and direct PHP injection through markup is already possible without Safe Mode in that configuration.

This issue only affects sites that meet all of the following conditions:

• cms.safe_mode is enabled (a deliberate opt-in for demos or untrusted-editor scenarios)
• The site has at least one backend user with CMS markup editing access who is not intended to be trusted as a full administrator
• The site has at least one existing superuser account whose session the lower-privileged user can impersonate