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9.2

Watchguard Fireware OS Access Portal permits remote memory overwrite

CVE-2026-93866 · published 5 days ago
Summary

The Access Portal feature in Watchguard Fireware OS can be tricked into writing data outside its intended memory area if someone sends a specially crafted request. This could allow an unauthenticated attacker to affect the device’s operation. Disable the Access Portal if not needed or apply the vendor’s update that corrects the handling of these requests.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
VendorProductAffected versions
watchguard fireware os < 2026.4
< 12.5.22
Original advisory text
Fireware OS Pre-Authentication Integer Overflow in Access Portal Allows Out-of-Bounds Write
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.
References
Fix within
Internet-facing 14 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit (estimated)
  • Gives an attacker full control (estimated)
Severity
9.2 Critical
Exploitation
<1% chance of attack within 30 days
Type
CWE-190Integer Overflow
CWE-288Authentication Bypass Using Alternate Path
CWE-787Out-of-bounds Write
Timeline
Published27 Oct 2026
Updated30 Oct 2026
First seen27 Oct 2026
Sources
CVE-2026-93866 · NVD
CVE-2026-93866 · MITRE
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