CVE-2026-46441

EUVD-2026-35109 · Published May 14, 2026

FlowiseAI has Mass Assignment in Assistant Update Endpoint that Allows Cross-Workspace Resource Reassignment

Summary

A Mass Assignment vulnerability exists in the assistant update endpoint of FlowiseAI.

The endpoint allows authenticated users to modify server-controlled properties such as workspaceId, createdDate, and updatedDate when updating an assistant resource.

Due to missing server-side validation and authorization checks, an attacker can manipulate the workspaceId field and reassign assistants to arbitrary workspaces. This breaks tenant isolation in multi-workspace environments.

Details

The endpoint responsible for updating assistants:

PUT /api/v1/assistants/{assistantId}

accepts a JSON request body containing assistant metadata.

However, the server does not restrict which properties may be modified by the client. As a result, user-controlled request bodies can include additional fields that should normally be controlled only by the backend.

Server-controlled fields that can be manipulated include:

workspaceId
createdDate
updatedDate

These fields appear to be directly mapped to the underlying database entity without strict DTO whitelisting or authorization checks.

For example, the following request body was accepted:

{
  "details": "",
  "credential": "11ca7fef-c9b1-4c87-aa54-e547aed8a249",
  "iconSrc": null,
  "type": "CUSTOM",
  "createdDate": "2026-03-06T17:31:04.000Z",
  "updatedDate": "2026-03-06T17:31:55.000Z",
  "workspaceId": "11111111-2222-3333-4444-555555555555"
}

This indicates that internal, server-controlled properties can be modified by an authenticated user.

PoC

Authenticate to the Flowise interface.
Capture the request used to update an assistant:

PUT /api/v1/assistants/<ASSISTANT_ID>
Content-Type: application/json

Modify the request body by injecting server-controlled fields:

{
  "details": "",
  "credential": "11ca7fef-c9b1-4c87-aa54-e547aed8a249",
  "iconSrc": null,
  "type": "CUSTOM",
  "createdDate": "2026-03-06T17:31:04.000Z",
  "updatedDate": "2026-03-06T17:31:55.000Z",
  "workspaceId": "11111111-2222-3333-4444-555555555555"
}

3.Send the request.

Observe that the response accepts and persists the attacker-controlled workspaceId and metadata fields.

Impact

This vulnerability allows authenticated users to manipulate internal attributes of assistant resources.

Confirmed impacts include:

Cross-workspace reassignment of assistants (workspaceId)
Unauthorized modification of metadata (createdDate, updatedDate)

In multi-tenant deployments, this may allow an attacker to move assistants between workspaces without authorization, breaking tenant isolation boundaries.

Technologies

Flowiseai FlowiseFlowise Flowise

Weaknesses

CWE-915CWE-639CWE-284

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access

T1190Exploit Public-Facing Application

References

Potentially impacted assets

See if this affects your attack surface

Latest trending attack

Criticalyesterday

Google Brotli decoder - Remote Code Execution via compressed requests (Exploitation Check)

This control is the second step of the Patrowl response to CVE-2026-111497 (Node2Shell). It complements the first control of 22 October 2026, which focused on the Node.js runtime, and does not replace it. Why a second control CVE-2026-111497 is an out-of-bounds write in the Google Brotli decoder, the library that decompresses Brotli ("br") data. It was first published as a Node.js vulnerability, because Node.js bundles this decoder. Later publications showed that the flaw is in the library itself. Every product that embeds an affected version of the decoder is concerned, whatever its language or vendor. A public proof of concept demonstrates code execution. Any server that decompresses request bodies sent with "Content-Encoding: br" exposes the decoder to unauthenticated attackers. Known cases include Express 5 and NestJS 11 on Node.js, Koa and Fastify setups, Bun, Envoy and Istio with request decompression enabled, and any application or reverse proxy that decodes Brotli request bodies with an affected library. The flaw also works in the other direction. A malicious server can compromise an unpatched client that decodes a Brotli response, for example Node.js fetch(), Python clients (requests, httpx, aiohttp, Scrapy) with the Brotli or brotlicffi package, or libcurl builds with Brotli support. What this control checks Patrowl sends small, valid Brotli-compressed requests to each asset and observes whether the server decodes them. The check does not depend on the technology: it detects the behaviour, whatever the stack behind it. These requests are what any legitimate client could send. They never reach the vulnerable code path and cannot affect the availability of the service. How to read the result Potentially impacted means the asset decodes Brotli request bodies: the attack surface is exposed. It does not confirm that the asset is vulnerable. The version of the Brotli decoder in use is not visible from the outside. This check covers applications that parse request bodies on their root path. A Not impacted result does not rule out exposure on other routes, nor on the client side. Checking the versions on the servers remains the only exhaustive verification. Affected and fixed versions Google Brotli 1.0.3 to 1.2.0 are affected, fixed in 1.0.10, 1.1.1 and 1.2.1. Fixed releases of the main products embedding it: Node.js 22.23.4, 24.22.1 and 26.12.1 (end-of-life lines 20.x and older and 25.x receive no fix), Bun 1.4.4, Envoy 1.37.8, 1.38.6, 1.39.3 and 1.40.0, Istio 1.29.9, 1.30.6 and 1.31.2, Python Brotli 1.2.1 and brotlicffi 1.2.1.0. Products that link against the system library depend on the Brotli package of the Linux distribution. Recommendations Update every component that embeds the Brotli decoder (only real fix). Start with the assets flagged by this control. Restart the processes after the update. Rebuild containers, single-executable applications and appliances that bundle an affected runtime or library. Reduce the exposure until the update is deployed. Reject requests with "Content-Encoding: br" at the reverse proxy, load balancer or WAF, case-insensitively and including lists such as "gzip, br". On Envoy and Istio, disable request decompression for Brotli. Review outbound calls. List the features that fetch content from servers you do not control, and patch the services that host them first.