Vulnerability · Published Oct 27, 2026 · Assigned by WatchGuard
CVE-2026-103593Fireware OS Stack Buffer Overflow in Logging Service Allows Remote Code Execution
Critical 9.1
In plain English
A critical-severity stack buffer 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 0.1% (higher than 1% of all known vulnerabilities).
Severity (CVSS 4.0)9.1Critical
Exploit odds (30 days)0.1%top 99.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
A stack-based buffer overflow vulnerability in the Fireware OS logging service allows a network-adjacent attacker who can impersonate or intercept traffic to the configured log server to execute arbitrary code with root privileges by presenting a specially crafted certificate.
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-121, CWE-787 · Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H
References
- https://psirt.watchguard.com/CVE-2026-103593 vendor-advisory