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Brocade Fabric OS EUVDEUVD-2026-94697

| CVE-2026-87660 HIGH
Incorrect Permission Assignment for Critical Resource (CWE-732)
2026-10-08 sirt@brocade.com GHSA-jf7h-33c6-ggh7
7.0
CVSS 4.0 · Vendor: brocade
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Attack ChainAIDerived

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

  1. Access
    Obtain low-privilege shell on FOS switch
  2. Exploit
    Access insecurely-permissioned diagnostic kernel module
  3. Execution
    Invoke privileged hardware test or blade reset
  4. Impact
    Disrupt storage fabric operations

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V13 - Configuration Permission assignment review
Exploitation Conditions

Requires an authenticated low-privilege local account (PR:L) on a Brocade switch running an affected Fabric OS build (before 9.2.2d, or 10.0.0 through 10.0.0a1); the vulnerable diagnostic kernel module subsystem is a standard FOS component. No user interaction is needed (UI:N). Exploitation is limited to actors who already hold shell/CLI access to the device - it is not described as remotely unauthenticated - and the description scopes the attacker to a 'local user,' which contradicts the input vector's AV:A and should be confirmed. Impact is restricted to integrity/availability (hardware tests, error conditions, blade resets, fabric disruption); no data disclosure is enabled.

Impact

This is a moderate-risk, locally-exploitable flaw rather than an urgent internet-facing emergency. The CVSS 4.0 base score of 7.0 (HIGH) is driven by high integrity and availability impact (VI:H/VA:H) with no confidentiality impact (VC:N), and requires only low privileges (PR:L) with no user interaction. A notable conflict exists in the source data: the vendor CVSS vector uses AV:A (adjacent network), but the description explicitly states 'an unprivileged local user' and attributes the flaw to improper file permissions on a kernel module (CWE-732), which points to local vector (AV:L) - verify the true attack surface with Broadcom, as this materially affects reachability. No EPSS score, CISA KEV listing, or public POC is present in the provided data, so there is no evidence of active exploitation - exploitation status is 'no public exploit identified at time of analysis.' Combined with the requirement for pre-existing authenticated access to the switch, real-world priority is moderate: patch in normal maintenance cycles rather than emergency, prioritizing SAN switches where untrusted or lower-tier operators hold shell/CLI accounts.

Exploit ScenarioDerived

An unprivileged but authenticated local user on a Brocade Fibre Channel switch leverages insecure permissions on the diagnostic kernel module subsystem to invoke privileged hardware diagnostic tests normally restricted to administrators. By forcing error conditions or resetting hardware blades, the user disrupts storage fabric operations, causing a denial of service to attached storage traffic. No public exploit code was identified in the provided data, and the attack requires prior low-privilege access to the device.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 08, 2026

Authenticated low-privilege local users on Brocade Fabric OS switches can abuse the diagnostic kernel module subsystem to invoke privileged hardware tests, force system error conditions, perform hardware blade resets, and disrupt storage fabric operations, because those interfaces ship with improper file permissions and lack authorization checks (CWE-732). Only devices running FOS builds before 9.2.2d, or in the 10.0.0 through 10.0.0a1 range, are affected, and exploitation requires an existing account with shell/CLI access on the switch rather than unauthenticated network reachability. No public exploit code or confirmed active exploitation has been identified at time of analysis (no CISA KEV entry), and the CVSS:3.1 assessment (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H) places this at moderate risk: the impact is confined to integrity and availability, with no confidentiality or data-disclosure component.

RemediationAI

Vendor-released patch: 9.2.2d (all 9.x builds before it are vulnerable); for the 10.x line, affected devices in the 10.0.0 through 10.0.0a1 range must be moved to the fixed 10.x build identified in Broadcom/Brocade advisory 39155 at https://support.broadcom.com/external/content/SecurityAdvisories/0/39155 - no exact 10.x fix version is stated in the available source data, so confirm the target release against the vendor advisory before upgrading. Upgrade in a maintenance window: FOS firmware changes on SAN switches require a reboot or failover and can disrupt fabric traffic paths, so plan for redundant-fabric or ISL-level rolling upgrades. Until patching is complete, the most effective compensating control is reducing the number of local accounts that can reach a shell: audit and remove unnecessary user accounts, restrict shell/CLI roles to the minimum set of administrators via FOS RBAC role definitions, and disable non-administrative interactive access where operationally possible (trade-off: this limits legitimate service and diagnostic workflows). Because the defect is a missing authorization check in the diagnostic module subsystem rather than a configurable service, there is no supported way to disable only the vulnerable interfaces without degrading normal switch diagnostics; blocking management-plane access (SSH/console) to trusted hosts is a weaker but useful supplement, and it will not stop an attacker who already holds a valid account. Enable and monitor FOS audit logging for diagnostic command execution and unexpected blade resets so that any attempted abuse by an existing low-privilege account is at least detectable.

Affected VersionsENISA

Fabric OS 10.0.0 ≤10.0.0a1
Fabric OS 0 <9.2.2d

Affected Packages

euvd fabric_os fix: 9.2.2d

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

The flaw is rooted in CWE-732 (Incorrect Permission Assignment for Critical Resource) compounded by a missing authorization check in Fabric OS's diagnostic kernel module subsystem - the component that exposes low-level hardware self-tests, error-injection paths, and blade control to user space. Because the device nodes or module-exposed interfaces backing those routines are reachable by non-privileged local accounts and the kernel-side handlers do not validate caller privilege, any user with CLI/shell access can drive operations that are intended to be reserved for administrative or service-level execution: running privileged diagnostic hardware tests, forcing error conditions, resetting hardware blades, and degrading storage fabric behaviour. FOS is the embedded switch operating system used across Brocade (Broadcom) SAN and Fibre Channel switches, so the affected attack surface is present on every switch running a listed build. Notably, the CVSS 4.0 vector supplied in the source data uses AV:A (adjacent network), while the authoritative independent assessment and the vendor description both scope the attacker as a local user, which resolves to AV:L; the AV:A value should be treated as unconfirmed pending vendor clarification. The CWE-732 root cause also explains the missing authorization: permissions on the diagnostic interfaces are misconfigured, so the privilege boundary that should gate them is simply absent.

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Severity by source

Vendor (brocade) PRIMARY 7.0 HIGH
CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
vuln.today AI 7.1 HIGH

Description states an unprivileged local user, so AV:L and PR:L; impact is integrity/availability (hardware reset, fabric disruption) with no confidentiality, so C:N/I:H/A:H.

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

Primary rating from Vendor (brocade).

CVSS VectorVendor: brocade

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

Lifecycle Timeline

2
Patch available
Oct 08, 2026 - 05:15 EUVD
CVE Published
Oct 08, 2026 - 04:17 cve.org
HIGH 7.0

DescriptionCVE.org

An improper file permission and missing authorization vulnerability exists in the diagnostic kernel module subsystem of Brocade Fabric OS versions before 9.2.2d and 10.0.0 through 10.0.0a1. An unprivileged local user can invoke privileged hardware tests, force system error conditions, reset hardware blades, or disrupt storage fabric operations.

Executive ViewAI

Why It Matters

Brocade Fabric OS switches running versions prior to 9.2.2d or 10.0.0 through 10.0.0a1 contain a high-severity flaw that allows an authenticated local user with low privileges to disrupt storage fabric operations, force system errors, and reset hardware blades. This could lead to unplanned storage downtime, impacting business-critical applications and data availability. Leadership should prioritize mitigation because these switches are core to SAN infrastructure, and a single malicious or careless insider could cause significant operational disruption.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations include: restrict local shell/CLI access to trusted administrators only; enforce least privilege by removing unnecessary accounts; audit and monitor for unauthorized execution of diagnostic kernel module commands; apply network segmentation to limit lateral movement; and maintain enhanced logging for hardware reset events.

Threat Intelligence Overview

EPSS Score
0.1%
Top 98% exploitable
Prevalence
Medium
Brocade Fabric OS runs on enterprise Fibre Channel SAN switches, common in data centers
Data Quality
6 sources
Confidence: High

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 0.1%
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
Controlled
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

35
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +35
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0
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