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Improper Mass Assignment in Flowise Cloud Account Registration
CVE-2026-41267 is an improper mass assignment / JSON injection vulnerability in the Flowise Cloud account registration endpoint affecting versions prior to 3.1.0. During account creation, the endpoint improperly accepts attacker-supplied server-managed fields and nested objects instead of strictly enforcing an allowlist of client-settable properties. As a result, an unauthenticated attacker can submit crafted registration data that manipulates sensitive internal attributes such as ownership metadata, timestamps, organization association, and role mappings. In a multi-tenant deployment, this breaks intended trust boundaries by allowing client control over fields that should be assigned exclusively by the server.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation allows an unauthenticated attacker to tamper with security-relevant account attributes at registration time. The attacker may be able to influence tenant or organization association, ownership metadata, timestamps, and role mappings, undermining authorization assumptions in a multi-tenant environment. Based on the provided advisory context and CVSS vector, the impact can extend to high confidentiality, integrity, and availability consequences if manipulated role or tenancy data enables unauthorized access, privilege abuse, cross-tenant impact, or disruption of normal service behavior.
If you can’t patch tonight, do this now.
If immediate upgrade is not possible, reduce exposure of the vulnerable registration endpoint where feasible and implement compensating controls at the application or API gateway layer to reject unknown JSON properties and nested objects during account creation. Perform server-side validation to strip or ignore client-supplied values for privileged fields, and review newly created accounts for anomalous organization bindings, ownership metadata, timestamps, or role assignments. In multi-tenant environments, audit authorization logic to ensure tenant isolation does not rely on client-controllable registration data.
Patch, then assume compromise.
Upgrade Flowise Cloud to version 3.1.0 or later, which fixes the vulnerability. The registration endpoint should enforce strict server-side allowlisting of accepted fields, reject unexpected properties and nested objects, and ensure that security-sensitive attributes such as ownership metadata, timestamps, organization identifiers, and role mappings are derived exclusively on the server and cannot be overridden by client input.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
4 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.