Vulnerability · Published Oct 27, 2026 · Assigned by WatchGuard

CVE-2026-103594Fireware OS Stack Buffer Overflow in WireGuard Configuration Allows Remote Code Execution

Critical 9.5

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 0.4% (higher than 38% of all known vulnerabilities).

Severity (CVSS 4.0)9.5Critical

Exploit odds (30 days)0.4%top 62.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

A stack-based buffer overflow vulnerability in Fireware OS's WireGuard configuration processing allows a remote attacker that has man-in-the-middle TLS-decrypted access between the Firebox and WatchGuard Cloud to create a Denial of Service condition and potentially execute arbitrary code by tampering with a FireCloud Gateway configuration payload.

Affected products (as reported)

Vendor	Product	Versions
WatchGuard	Fireware OS	2026.2 – before 2026.412.12 – before 12.12.4

Weakness: CWE-121, CWE-1284, CWE-787 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

References

https://psirt.watchguard.com/CVE-2026-103594 vendor-advisory