CVE-2026-90441 is a high severity missing authorization flaw in WatchGuard Fireware, scored 8.1. The record names no fixed version. 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
- WatchGuard Fireware, in the wgagent management daemon. The record lists no version ranges.
Severity in the record: High (8.1), vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Weakness: CWE-200, CWE-400, CWE-862.
Fix: The record names no fixed version. See the WatchGuard PSIRT page.
How to check if you're exposed
- Check the Fireware OS version in the Web UI System Status page or with the CLI.
- Compare with the WatchGuard PSIRT 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 read-only and guest administrator accounts.
- Record the change, then recheck the version to confirm it took effect.
Why it matters
Session initialization in the wgagent daemon lacks an authorization check. A low-privileged user, even a read-only or guest administrator, can send a crafted management API request that crashes wgagent and reads files the daemon can access. Weakness classes: CWE-862, CWE-200 and CWE-400. Rated 8.1, with high confidentiality and availability impact.
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
Does a read-only account matter?
Yes. The record includes read-only and guest administrator accounts.
Sources
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WatchGuard: PSIRT CVE-2026-90441
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Safeguard Gold: CVE-2026-90441
Last reviewed: 18 October 2026.
