Critical severity · published Oct 27, 2026
CVE-2026-93866
Fireware OS Pre-Authentication Integer Overflow in Access Portal Allows Out-of-Bounds Write
New
9.2
CVSS
–
EPSS
No
On KEV
Description
An integer overflow vulnerability in the WebSocket connection handling used by WatchGuard Fireware OS's Access Portal allows a remote, unauthenticated attacker to write beyond the bounds of a heap buffer by sending a specially crafted request while the Access Portal feature is enabled.
Exploitation
Is it being used?
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FO
Fireware OS · WatchGuard
2025.1 before 2026.4; 12.0 before 12.12.4; 12.0 before 12.5.22 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-93866
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-93866
psirt.watchguard.com
https://psirt.watchguard.com/CVE-2026-93866
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