CVE-2026-94582

Executive Summary

CVE-2026-94582 is a memory buffer overflow (CWE-120) in the internal diagnostic and route validation routines of the Fabric Shortest Path First (FSPF) protocol component in Brocade Fabric OS versions before 10.0.1. The vulnerable code path is part of internal diagnostic functionality and is not directly reachable through standard user interfaces or CLI management commands, meaning an attacker must first chain or link other vulnerabilities to deliver crafted diagnostic state payloads. Successful exploitation can cause a heap- or stack-based memory overrun, leading to a routing daemon crash (Denial of Service) or potential arbitrary code execution within the context of the routing daemon — a high-impact outcome for SAN fabric infrastructure.

Technical Analysis

The vulnerability resides in the FSPF protocol component of Brocade Fabric OS. FSPF is the link-state routing protocol used within Fibre Channel fabrics to compute shortest paths between switches; it operates in the control plane of the fabric and is handled by a routing daemon on each switch. CVE-2026-94582 is classified under CWE-120 (Buffer Copy without Checking Size of Input, commonly termed "Classic Buffer Overflow").

According to the NVD description, the flaw exists in "internal diagnostic and route validation routines" associated with FSPF. The root cause is an input processing flaw: incoming or internally routed diagnostic state payloads are permitted to exceed allocated memory boundaries. Because the vulnerable routines are reached only through internal diagnostic functionality — not via standard user interfaces or CLI management commands — the flaw is not directly triggerable by an unauthenticated remote user interacting with normal management surfaces.

The memory-safety impact is described as a heap- or stack-based memory overrun. This distinction matters for exploitation: a stack-based overrun can corrupt return addresses and saved control data, while a heap-based overrun can corrupt allocator metadata and adjacent heap objects. The NVD description does not specify which allocation region is affected per input, so defenders should treat both as possible. The consequence stated is either a daemon crash (availability loss) or potential arbitrary code execution within the routing daemon's process context.

No CVE description detail is available regarding the precise maximum payload size, the specific structure or field that overflows, or the exact protocol encoding of the "diagnostic state payloads." Those implementation details are not disclosed and must not be inferred. What is clear from the data is the vulnerability class (unchecked copy leading to memory corruption), the component (FSPF in Fabric OS), the exposure model (internal diagnostic code path requiring chaining), and the version boundary (< 10.0.1).

From a CVSS modeling standpoint, the NVD base vector is not published (CVSS Score: N/A; Vector: N/A). Based on the described characteristics, a provisional vector of CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H is a reasonable analytic projection: network-reachable in principle, high attack complexity (requires chaining another vulnerability to reach the internal path), no privileges or user interaction required once the chain is established, and high confidentiality, integrity, and availability impact because code execution in the routing daemon controls fabric topology computation and inter-switch routing behavior. This projection is analytic and is NOT an official NVD score.

CWE-120 has a well-known history of leading to remote code execution when input length is not validated before a copy into a fixed-size buffer. In routing daemons specifically, exploitation historically enables route table manipulation, neighbor adjacency disruption, and in some cases full process takeover, which in a storage fabric can translate to fabric segmentation, traffic redirection, or denial of storage access.

Exploitation Scenarios

No public PoC, exploit code, or Nuclei template is available for CVE-2026-94582. The attack chain below is inferred from the vulnerability class and the NVD description, which states that the attacker must "chain or link other vulnerabilities to exploit this internal diagnostic."

1. Reconnaissance / target identification. An adversary maps Brocade Fibre Channel fabrics and identifies switches running Fabric OS versions before 10.0.1. Because standard interfaces and CLI management commands do not reach the vulnerable path, reconnaissance focuses on identifying a pathway into the switch — for example, an initial foothold vulnerability (a separate CVE) that grants the ability to inject, route, or manipulate diagnostic state payloads, or a lesser-privileged access that can influence internal diagnostic processing.

2. Triggering the flaw class. Once a chaining vulnerability provides access to the internal diagnostic/route-validation path, the attacker supplies a crafted diagnostic state payload whose length exceeds the allocated destination buffer. Per the description, the payload may be either "incoming or internally routed." The unchecked copy overruns the intended memory boundary (heap or stack). No specific wire format, field name, or size is disclosed, so payload construction cannot be described at the byte level — only at the vulnerability-class level.

3. Payload / execution method. This is the classic unchecked-buffer-copy class: the oversized payload overwrites adjacent memory. The attacker may aim merely for a daemon crash (overwriting critical data) or, if they can control the overflowed bytes and locate a suitable target in process memory, for control-flow hijack leading to arbitrary code execution in the routing daemon context. Success depends on memory layout, mitigations present in Fabric OS, and the specifics of the chaining vulnerability.

4. Post-exploitation impact. If only the crash path is hit, the FSPF routing daemon terminates, disrupting fabric route computation — a denial of service. If exploitation reaches code execution, the attacker operates as the routing daemon, enabling manipulation of FSPF route calculation, disruption of switch-to-switch adjacencies, and potential lateral movement across the storage fabric. Given the fabric's role in SAN connectivity, this can cause storage path loss for downstream hosts.

Impact Assessment

The vulnerability maps to high confidentiality, integrity, and availability impact in the projected vector (C:H/I:H/A:H), with high attack complexity (AC:H) reflecting the requirement to chain another vulnerability and reach an internal diagnostic path, and no privileges or user interaction required once that path is achieved. Scope is unchanged (S:U): the affected component is the routing daemon within the same Fabric OS security authority.

Business impact centers on SAN availability and integrity. Fabric OS switches are the backbone of Fibre Channel storage networks. A daemon crash can interrupt route computation and disrupt inter-switch links (ISLs), degrading or severing host-to-storage paths. If arbitrary code execution is achieved, the blast radius expands to the integrity of routing decisions and potentially to the broader fabric, enabling persistent disruption, traffic redirection, or further pivoting. Environments with mission-critical, low-latency storage workloads (databases, virtualization clusters, backup infrastructure) face the most acute operational risk.

Blast radius is bounded by the initial chaining requirement: an attacker cannot reach this flaw through standard interfaces alone, so the effective exposure is gated by the presence of a separate exploitable entry point. Fabrics that are segmented and have strict management-plane access controls reduce the exploitability window. No EPSS elevation is observed (EPSS 0.00127, ~2.0 percentile), and there is no CISA KEV entry and no known exploit-in-the-wild evidence at the time of writing. This suggests low current exploitation activity but does not reduce the severity of a successful chain, since the end-state impact is code execution in a routing daemon.

Detection Guidance

Because the vulnerable path is internal and not directly exposed via standard interfaces, host- and network-based detection should focus on two things: (a) anomalies in FSPF/router daemon behavior and process health, and (b) attempts to reach internal diagnostic functionality through whatever chaining vulnerability exists. Detection should prioritize daemon crashes, unexpected restarts, core dumps, and abnormal FSPF control-plane traffic.

Sigma Rule

title: Brocade Fabric OS FSPF Routing Daemon Crash or Abnormal Termination (CVE-2026-94582)
id: 8f3c1b2e-4a7d-4c9e-9b21-2f6a5d0e7c11
status: experimental
description: Detects abnormal termination, crash, or restart of the FSPF routing daemon on Brocade Fabric OS, which may indicate exploitation of CVE-2026-94582.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-94582
author: valtersit.com
date: 2026/01/01
logsource:
  product: brocade
  service: fabric_os
detection:
  selection_daemon:
    process|contains:
      - 'fspfd'
      - 'fabricd'
      - 'routing daemon'
  selection_event:
    message|contains:
      - 'core dump'
      - 'segmentation fault'
      - 'signal 11'
      - 'daemon restart'
      - 'unexpected termination'
      - 'abnormal exit'
  condition: selection_daemon and selection_event
falsepositives:
  - Planned maintenance restarts
  - Software upgrades
level: high

YARA Rule

rule CVE_2026_94582_Brocade_FSPF_Overflow
{
    meta:
        description = "Heuristic detection for oversized FSPF diagnostic state payloads targeting Brocade Fabric OS CVE-2026-94582"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-94582"
        date = "2026-01-01"
        severity = "high"

    strings:
        $fspf = "FSPF" ascii wide nocase
        $diag1 = "diagnostic state" ascii wide nocase
        $diag2 = "route validation" ascii wide nocase
        $fabric = "Fabric OS" ascii wide nocase

    condition:
        uint32(0) != 0x464c457f and
        filesize < 5MB and
        (
            ($fspf and $diag1) or
            ($fspf and $diag2) or
            ($fabric and $diag2)
        )
}

Suricata IDS Rule

alert tcp any any -> any 22 (msg:"CVE-2026-94582 Brocade Fabric OS FSPF Diagnostic Overflow Attempt"; flow:to_server,established; content:"FSPF"; nocase; content:"diagnostic"; nocase; distance:0; within:256; threshold:type limit, track by_src, count 1, seconds 60; classtype:attempted-admin; reference:cve,2026-94582; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-94582; sid:202694582; rev:1;)

Elastic Detection

sequence by host.name with maxspan=5m
  [ process where process.name : ("fspfd", "fabricd") and event.action == "start" ]
  [ process where process.name : ("fspfd", "fabricd") and event.action in ("crash", "terminated", "abnormal-exit") ]

Splunk SPL Query

index=brocade sourcetype=fabric_os:syslog
("fspfd" OR "fabricd" OR "routing daemon")
("segmentation fault" OR "core dump" OR "signal 11" OR "abnormal termination" OR "daemon restart" OR "unexpected termination")
| stats count min(_time) as first_seen max(_time) as last_seen by host, message
| where count >= 1
| convert ctime(first_seen) ctime(last_seen)
| sort - last_seen

Wazuh OSSEC Rule

<group name="brocade,fabric_os,cve-2026-94582,">
  <rule id="202610" level="12">
    <decoded_as>syslog</decoded_as>
    <match>fspfd|fabricd|routing daemon</match>
    <regex>segmentation fault|core dump|signal 11|abnormal termination|unexpected termination</regex>
    <description>CVE-2026-94582: Possible Brocade Fabric OS FSPF routing daemon crash or abnormal termination</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cve_2026_94582,</group>
  </rule>

  <rule id="202611" level="10">
    <decoded_as>syslog</decoded_as>
    <match>Fabric OS</match>
    <regex>diagnostic state|route validation</regex>
    <description>CVE-2026-94582: Suspected FSPF diagnostic/route validation payload processing anomaly</description>
    <group>cve_2026_94582,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor fix reference, workaround, or affected-version list is present in the tracked data; the only version boundary available is the NVD description's statement of "versions before 10.0.1."

1. Immediate mitigations.

• Upgrade Fabric OS to 10.0.1 or later, which the NVD description identifies as the fixed boundary; treat all versions before 10.0.1 as affected pending vendor confirmation.
• Because exploitation requires chaining another vulnerability to reach internal diagnostic functionality, harden and reduce the exposure of all primary entry points into the switch (management interfaces, remote access, and any externally reachable services). Closing chaining vulnerabilities directly reduces exploitability of this flaw.
• Restrict management-plane access to dedicated, tightly filtered networks and remove unnecessary remote access.
• Monitor for FSPF/routing daemon crash, restart, or core-dump events and investigate any occurrence as a potential exploitation attempt.

2. Patch / upgrade steps.

• Track the Brocade (Broadcom) security advisory for CVE-2026-94582 for the official fixed release and any interim guidance. No vendor advisory URL is provided in the source data; consult the vendor's security advisory portal.
• Validate the fabric's supported upgrade path to Fabric OS 10.0.1+, schedule upgrade windows for redundant switch pairs, and verify FSPF adjacency and route stability after upgrade.
• Confirm patch status per switch with the vendor's versioning guidance; do not rely solely on the version string.

3. Long-term hardening.

• Segment storage fabrics and isolate management planes from data/user networks.
• Maintain an inventory of Fabric OS versions across all switches and enforce a patch SLA for the SAN fabric tier.
• Enable and forward switch audit and daemon logs (including FSPF/routing daemon events) to a central SIEM with the detections above.
• Apply the principle of least privilege to switch management accounts and disable unused services and interfaces.
• Periodically reassess because exploitability is gated by chaining vulnerabilities: improvements to eliminate other footholds also mitigate this CVE's practical risk.

References

• NVD — CVE-2026-94582: https://nvd.nist.gov/vuln/detail/CVE-2026-94582
• CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow): https://cwe.mitre.org/data/definitions/120.html
• MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
• Brocade / Broadcom Security Advisories portal (vendor advisory for Fabric OS; confirm the CVE-2026-94582 advisory and fixed version 10.0.1): https://www.broadcom.com/support/fibre-channel-networking/security-advisories
• CISA Known Exploited Vulnerabilities Catalog (CVE-2026-94582 not listed at time of writing; monitor for addition): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

No public PoC, exploit code, or Nuclei template is available for CVE-2026-94582, and there is no known threat actor campaign or exploit-in-the-wild evidence in the provided data. EPSS is 0.00127 (~2.0 percentile), and the CVE is not in the CISA KEV catalog, indicating low observed exploitation activity to date.