Critical Authentication

CVE-2026-87659 — Missing Authentication for Critical Function in Broadcom Fabric Operating System

A critical authorization bypass vulnerability exists in the Management Server handling of Brocade Fabric OS versions before 10.0.1. A compromised switch connected to the fabric can transmit crafted inband Fibre Channel vendor-unique CT (Common Transport) management requests to bypass administrative authentication. Successful exploitation allows an unauthorized peer switch to execute administrative actions on the target device, including resetting administrative passwords, initiating system reboots, and triggering firmware downloads.

Published Oct 8, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: brocade

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+2
Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.24%

ahead of 14% of scored CVEs · Oct 14, 2026

Affects

Broadcom

Fabric Operating System and 1 more

CVSS base

9.8

Critical · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Broadcom Fabric Operating System, Brocade Fabric OS).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (authentication), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Broadcom	Fabric Operating System	< 10.0.1	Vulnerable	NIST National Vulnerability Database
Brocade	Fabric OS	< 10.0.1	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.1	CVSS 4.0	High	—	—	sirt@brocade.com via NIST National Vulnerability Database
7.1	CVSS 4.0	High	—	—	brocade via CVE Program (cve.org) e CISA ADP
9.8	CVSS 3.1	Critical	3.9	5.9	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-306 · Missing Authentication for Critical Function

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.24%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Review authentication logs: logins without MFA, anomalous sessions and recently created accounts.

web/proxy/WAF logsnetwork IDS/IPSauthentication logs

Timeline

What happened to this CVE, newest first.

2026
Affected products added · brocade/fabric os
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Affected products added · broadcom/fabric operating system
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 7.1 → 9.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · Undergoing Analysis → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record published
Oct 13, 2026
CVSS changed · 7.1
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Undergoing Analysis
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Oct 8, 2026 · brocade

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

support.broadcom.com/external/content/SecurityAdvisories/0/39153
Vendor Advisory, NIST National Vulnerability Database

Elsewhere on this site

Broadcom
every CVE for this vendor

Authentication
same class

CWE-306
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-94587 A buffer overflow vulnerability exists in the WebTools administrative interface handling... 7d
High CVE-2026-94579 An OS command injection vulnerability exists in the PAM (Pluggable Authentication Module) session... 7d
High CVE-2026-94577 A privilege escalation vulnerability exists in the internal Command-Line Interface (CLI)... 7d
Medium CVE-2026-94581 An OS command injection vulnerability exists in the REST API management interface of Brocade... 7d
Medium CVE-2026-94586 A command injection vulnerability exists in the WebTools administrative interface handling... 7d
High CVE-2026-94585 An authentication bypass vulnerability exists in the web management interface of Brocade Fabric... 7d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-87659 is "Missing Authentication for Critical Function in Broadcom Fabric Operating System", rated Critical. It affects Fabric Operating System (Broadcom); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 0.24% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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