Vulnerability · Published Oct 27, 2026 · Assigned by WatchGuard
CVE-2026-93866Fireware OS Pre-Authentication Integer Overflow in Access Portal Allows Out-of-Bounds Write
Critical 9.2
In plain English
A critical-severity integer overflow in Fireware OS from WatchGuard. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities).
Severity (CVSS 4.0)9.2Critical
Exploit odds (30 days)0.5%top 56.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| WatchGuard | Fireware OS | 2025.1 – before 2026.412.0 – before 12.12.4 |
| WatchGuard | Fireware OS | 12.0 – before 12.5.22 |
Weakness: CWE-190, CWE-288, CWE-787 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
References
- https://psirt.watchguard.com/CVE-2026-93866 vendor-advisory