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
0.4%
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?
Exploit prediction (EPSS)0.4% · higher than 39% of CVEs
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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