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FastBee EUVDEUVD-2026-115901

| CVE-2026-121556 HIGH
Authorization Bypass Through User-Controlled Key (CWE-639)
2026-11-03 VulnCheck
8.7
CVSS 4.0 · Vendor: VulnCheck
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Authenticate as low-privilege tenant user
  2. Exploit
    Enumerate sequential auto-increment product IDs
  3. Execution
    Call unguarded ProductController by-ID endpoint
  4. Impact
    Read MQTT credentials, overwrite tenant_id, or delete products

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Object-level authorization, IDOR prevention
Exploitation Conditions

Requires a valid authenticated FastBee tenant account (PR:L) and a multi-tenant deployment where other tenants' products exist. The specific trigger per the source references is that the ProductController by-ID endpoints (detail/credential/edit/delete, around ProductController.java lines 77-141) enforced only RuoYi permission strings and omitted the tenant-ownership scoping that the list query applies at the service layer; combined with auto-increment product primary keys this lets any tenant enumerate and act on foreign IDs. Limiting factors: attacker must be logged in as a tenant user, and global-scope roles (admin/manager/visitor) are legitimately all-access, so the issue specifically affects cross-tenant isolation; no non-default configuration is otherwise needed. The only complete fix per the evidence is the vendor patch adding ownership enforcement.

Impact

This is a genuine, actionable authorization flaw rather than an inflated high-CVSS score, but its reach is bounded. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N) is internally consistent with the description: exploitation is remote and low-complexity, requires no user interaction, but does require a valid authenticated tenant account (PR:L) - so this is not an unauthenticated internet-wide exposure. VC:H/VI:H are well supported (reading MQTT account/password/secret values, and overwriting product configuration including tenant_id), while VA:L reflects the product-deletion-with-cascading-rows capability. No EPSS score was provided in the input, so exploitation probability cannot be quantified here. The CVE is NOT in CISA KEV and no confirmed working exploit code is listed, so exploitation status is 'no public exploit identified at time of analysis' despite VulnCheck having published source-level analysis. The vuln.today decision label is 'this_week', which - combined with an available vendor patch, trivially enumerable auto-increment product IDs, and high confidentiality/integrity impact - makes this a near-term priority for anyone running multi-tenant FastBee, while the authentication requirement and the product's niche footprint keep it below emergency tier. No signals are internally conflicting; the main missing signal is EPSS.

Exploit ScenarioDerived

A low-privilege but authenticated FastBee tenant user iterates sequential (auto-increment) product IDs against the ProductController by-ID endpoints, which validated only permission strings and not tenant ownership. By doing so they read other tenants' MQTT account, password, and secret values, and can overwrite product configuration (including tenant_id) or delete products with cascading row deletion. No confirmed working exploit code is published, though VulnCheck released a source-level advisory identifying the vulnerable endpoints.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available

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AnalysisAIv1 – Nov 03, 2026

Cross-tenant object reference flaw in FastBee through 2.1.0 lets any authenticated tenant user read another tenant's MQTT account, password and secret values, and overwrite or delete foreign product records, by supplying or enumerating sequential product IDs. The by-ID endpoints in ProductController enforced only RuoYi permission strings and omitted the tenant-ownership scoping that the list query applies at the service layer, which yields high confidentiality and integrity impact with limited availability impact (reported CVSS 4.0 score 8.7; independently assessed as CVSS 3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L). Exploitation requires a valid tenant account on a multi-tenant deployment where other tenants' products exist, and no public exploit code or active exploitation was identified at time of analysis.

RemediationAI

Apply the vendor fix, which the evidence identifies as the only complete remediation: FastBee states patch availability and the ownership enforcement is delivered in commit 3393e3223965a9dc9682dfb2bd37635fffa0fbd2 (https://github.com/beecue/FastBee/commit/3393e3223965a9dc9682dfb2bd37635fffa0fbd2), which adds the IotDataAccessGuard and wires it into the product and device by-ID endpoints; a tagged patched release version is not stated in the available data, so confirm the build you deploy contains that commit or a later one carrying the guard. Because the check is implemented at the controller boundary rather than the service layer, verify after upgrading that every by-ID product and device route invokes the guard - service methods are also reached from MQTT broker threads and internal flows where no login context exists, so partial backports that only guard one controller leave the path open. Until the fix is deployed, the exposure is bounded by the prerequisites described in the advisory: only authenticated tenant accounts on multi-tenant deployments can reach foreign products, and accounts holding RuoYi all-data scope roles (admin, manager, visitor) are global by design, so limiting who holds tenant-scoped accounts and running single-tenant installations reduces but does not remove the risk, and doing so also removes the tenant separation the platform is meant to provide. Rotate the MQTT accounts, passwords and secrets of any product that may have been enumerated, since leaked credentials allow connecting to the broker as that device.

Affected VersionsENISA

FastBee 0 ≤2.1.0

Affected Packages

euvd fastbee no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

FastBee is a Java/Spring Boot IoT platform built on the RuoYi framework, with MyBatis mappers over a relational store and an MQTT broker component that consumes product and device credentials. The flaw is CWE-639 (authorization bypass through a user-controlled key): the product detail, credential, edit and delete handlers in ProductController (roughly lines 77-141 of the 2.1.0 tree) looked up records by primary key from the request and checked only permission strings, while the corresponding service and mapper layers (ProductServiceImpl lines 72-92, ProductMapper.xml lines 37-67) applied the caller's tenant scope only to list queries. Because product IDs are auto-increment, a tenant user can walk the key space and reach other tenants' rows; the returned data includes the MQTT account, password and secret used to authenticate the product, and writes can reassign tenant_id or delete a product together with its cascading child rows. The vendor fix introduces an IotDataAccessGuard component invoked at the controller boundary rather than in the service, because service methods are also called from MQTT broker threads and internal flows where no login context exists; the guard treats RuoYi data scope "1" (all-data) roles such as admin, manager and visitor as legitimately global, grants shared users access to devices but deliberately withholds connection credentials, and applies the same ownership check to the device endpoints touched in the same commit. The practical consequence is that product credentials obtained through the IDOR can be used to connect to the broker as the victim's device, bypassing broker-side ACLs.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (VulnCheck) PRIMARY 8.7 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
vuln.today AI 8.3 HIGH

Authenticated tenant user (PR:L) over network with trivially enumerable sequential IDs (AC:L); exposes MQTT secrets (C:H), allows config/tenant_id overwrite (I:H), and product deletion gives partial availability impact (A:L); no scope change.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Vulnerable system: Confidentiality
High
Vulnerable system: Integrity
High
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

FastBee through 2.1.0 contains an insecure direct object reference vulnerability in ProductController that allows authenticated tenant users to access other tenants' products by supplying their product IDs. Attackers can enumerate sequential product IDs to read MQTT account, password, and secret values, overwrite product configuration including tenant_id, or delete products with cascading rows.

Executive ViewAI

Why It Matters

A cross-tenant access control flaw in FastBee version 2.1.0 allows any authenticated tenant user to read other tenants' MQTT credentials and tamper with their product data. This compromises the confidentiality and integrity of multi-tenant MQTT environments, eroding customer trust and potentially leading to data breaches or operational disruptions. Leadership should prioritize remediation to prevent unauthorized access and protect sensitive IoT device secrets.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

Prevalence
Low
niche open-source Chinese IoT platform, limited enterprise deployment footprint
Data Quality
4 sources
Confidence: Medium
EUVD NVD CVE.org Vulnrichment GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS N/A
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

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