---
id: "CVE-2026-93864"
kind: "vulnerability"
aliases: ["CVE-2026-93864"]
title: "WatchGuard Fireware OS: local link following lets a low-privileged process overwrite root files"
severity: "high"
cvss: 7.1
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "Fireware OS", "fixed": ["2026.4", "12.12.4"], "affected": ">= 2025.1, < 2026.4; >= 12.0, < 12.12.4", "ecosystem": "vendor"}, {"name": "Fireware OS (T15/T35)", "fixed": ["12.5.22"], "affected": ">= 12.0, < 12.5.22", "ecosystem": "vendor"}]
ecosystems: []
tags: ["firebox", "firewall-appliance", "fireware-os", "infrastructure", "local-privilege-escalation", "watchguard"]
not_affected_if: ["fireware-12.12.4-or-later", "fireware-2026.4-or-later", "no-watchguard-fireware", "t15-t35-12.5.22-or-later"]
published_at: "2026-10-27T16:17:32+00:00"
first_seen_at: "2026-10-27T16:33:07+00:00"
updated_at: "2026-10-27T16:36:27+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93864", "first_seen_at": "2026-10-27T16:33:07+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-27T16:36:27+00:00"}]
---

# WatchGuard Fireware OS: local link following lets a low-privileged process overwrite root files

A link following flaw in the firewall daemon of WatchGuard Fireware OS lets a local attacker who already runs code as a low-privileged system process plant a crafted file system object and trigger a list update. The attacker can then overwrite arbitrary files with root privileges and tamper with firewall IP set data, though the written content is partially constrained.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Fireware OS affected >= 2025.1, < 2026.4; >= 12.0, < 12.12.4 fixed 2026.4, 12.12.4
- vendor:Fireware OS (T15/T35) affected >= 12.0, < 12.5.22 fixed 12.5.22

## How to check

Check the Fireware OS version on the Firebox (Web UI System Status, or CLI 'show system' / WatchGuard System Manager). Exposed if on Default platforms >= 2025.1 and < 2026.4, or >= 12.0 and < 12.12.4; or on T15/T35 >= 12.0 and < 12.5.22.

## Fix

Upgrade Fireware OS to 2026.4 or later (2025.1/2026.x line), 12.12.4 or later (12.x), or 12.5.22 or later on T15/T35 models.

## Timeline

- 2026-10-27T16:33:07+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-93864
- 2026-10-27T16:36:27+00:00 analyst — Read WatchGuard PSIRT advisory: affected/fixed versions, not exploited per vendor; no PoC searched/found; no mitigations or workaround listed. Verified fix/products/who_affected from vendor text.

## Documents

- [advisory] WatchGuard PSIRT: CVE-2026-93864 Fireware OS Link Following in firewalld https://psirt.watchguard.com/CVE-2026-93864/

## From the sources

A link following vulnerability in WatchGuard Fireware OS’s firewall daemon allows a local attacker with code execution as a low-privileged system process to overwrite arbitrary files with root privileges, and to tamper with firewall IP set data, by planting a crafted file system object and triggering a list update. Written content is partially constrained.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_