CVE-2026-87666 is a high severity command injection flaw in Brocade Fabric OS, scored 8.0. The boundaries imply 9.2.2d or later on the 9.2 line and a release after 10.0.0a1 on the 10.0 line. Check your installed version against the affected list below, then patch or restrict access until you can. The record does not flag it as exploited.
What's affected
- Brocade Fabric OS before 9.2.2d.
- Brocade Fabric OS 10.0.0 through 10.0.0a1.
Severity in the record: High (8.0), vector CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Weakness: CWE-78.
Fix: The boundaries imply 9.2.2d or later on the 9.2 line and a release after 10.0.0a1 on the 10.0 line. Confirm exact builds in the advisory. The record gives the affected range only. The exact fixed builds are listed in the Broadcom advisory, which you should read before scheduling the upgrade.
How to check if you're exposed
- Fabric OS exposes its running version from the switch command line. The
firmwareshowcommand is the usual way to read it; confirm the command and output format against your Fabric OS release documentation. - Repeat on every switch, director and extension blade, since versions can differ across a fabric.
- Compare each version with the affected range above and with the fixed builds named in the Broadcom advisory.
Run these on every affected device, including ones in remote sites, labs and spares that are powered on.
What to do now
- Confirm the version of every affected system using the checks above.
- Read the vendor advisory linked in Sources and note the fixed version for your release line.
- Schedule the update, starting with systems that face untrusted networks or hold the most sensitive data.
- In the meantime: review which accounts hold administrative roles on Fabric OS devices and remove ones that are not needed.
- Record the change, then recheck the version to confirm it took effect.
Why it matters
The time and zone management code passes a timezone string to shell execution routines without sanitizing it. Shell metacharacters in that string reach the shell, which is CWE-78 OS command injection. The attacker needs a low-privilege administrative login and adjacent network access (the vector is AV:A). Impact is high on confidentiality, integrity and availability because the commands run with elevated privileges and escape the restricted management shell.
The record's KEV flag is false, so this post makes no claim that the flaw is exploited in the wild. That can change, so recheck the CISA catalog from time to time.
Network and management devices are patched less often than servers, because upgrades mean planned downtime. That gap is where a flaw like this stays open longest, so build the version check into your regular inventory.
The vector string in the record is a compact summary of how the flaw is reached and what it costs. AV is the attack vector (network, adjacent or local), PR is the privilege the attacker needs, and the C, I and A letters give the impact on confidentiality, integrity and availability. Read it against your own network layout rather than relying on the score alone.
After you patch
Patching is not the end of the job. Recheck the version on each system, because an upgrade that failed or rolled back looks the same as a success until someone looks. Keep the advisory link with your change record so the next reviewer can see why the update happened.
If you cannot patch soon, write down the reason, the compensating control you chose and a date to revisit. Exceptions without a date tend to become permanent.
Quick check
Why does a low-privilege account matter so much here?
Because the flaw lets that account leave the restricted management environment and run shell commands with elevated rights.
Sources
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Broadcom advisory: 39149
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Safeguard Gold: CVE-2026-87666
Last reviewed: 18 October 2026.
