CVE-2026-103593
WatchGuard Fireware OS
- WatchGuard Fireware OS
- Critical
- CVSS 9.1
- EPSS 0.1%
- Fixed version listed
Summary
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.
From the CVE record.
What to do
Fixed version listed
Affected products
| Product | Affected | Fixed in |
|---|---|---|
| WatchGuard Fireware OS (Default) | from 2025.1, before 2026.4; from 12.0, before 12.12.4 | 2026.4, 12.12.4 |
| WatchGuard Fireware OS (T15/T35) | from 12.0, before 12.5.22 | None listed |
Advisories and fixes
- Vendor advisory psirt.watchguard.com
Scores and signals
- Exploitation
- No known exploitation
- Severity
- Critical, CVSS 9.1 (v4.0, scored by WatchGuard)
- EPSS
- 0.1% chance of exploitation in the next 30 days (EPSS from FIRST, as of Oct 28, 2026)
- Weakness
- CWE-121: CWE-121; CWE-787: CWE-787
- Vendor
- WatchGuard, Fireware OS
Timeline
- First listed as critical by cve.now. Affected and fixed versions come from the CVE record, once one is published.