# CVE-2026-93864: WatchGuard Fireware OS arbitrary file overwrite via link following

Source: https://junglewise.ai/threats/cve-2026-93864-a-link-following-vulnerability-in-watchguard-fireware-os-s  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-93864 · Severity: info · Published 2026-10-27

WatchGuard Fireware OS is network firewall software that protects organizations by controlling and monitoring traffic. A vulnerability in the firewall daemon allows a local attacker who has already compromised a low-privileged system process to escalate privileges and overwrite critical files with root-level access, potentially disabling security controls or modifying firewall policies.

Technologies: [Watchguard Fireware OS](https://junglewise.ai/threats/technologies/fireware-os). Vendors: [Watchguard](https://junglewise.ai/threats/vendors/watchguard).

## Quick answers

**Is CVE-2026-93864 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-93864 being exploited in the wild.

**How severe is CVE-2026-93864?** Informational severity, published 27 October 2026.

**Which products and versions are affected?** Watchguard Fireware OS Default: 2025.1 through 2026.3, 12.0 through 12.12.3; T15/T35: 12.0 through 12.5.21.

**Is there a fix for CVE-2026-93864?** Yes: fixed in Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-93864 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-93864?** Check whether you run Watchguard Fireware OS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22

## Technical details

A link following vulnerability (CWE-59) in the firewall daemon's file handling allows a local attacker with code execution as a low-privileged system process to plant a crafted symlink and trigger a file update operation, causing the daemon to overwrite arbitrary files with root privileges. The attacker can exploit this to tamper with firewall IP set data or other system files; written content is partially constrained.

## Affected products

- WatchGuard Fireware OS Default: 2025.1 through 2026.3, 12.0 through 12.12.3; T15/T35: 12.0 through 12.5.21

## Timeline

- 2026-10-27: disclosed

## References

- [https://psirt.watchguard.com/CVE-2026-93864](https://psirt.watchguard.com/CVE-2026-93864)

## Related threats

- [WatchGuard Fireware OS integer overflow in WebSocket Access Portal](https://junglewise.ai/threats/cve-2026-93866-an-integer-overflow-vulnerability-in-the-websocket-connection)
- [WatchGuard Fireware OS authentication bypass in FireCluster daemon](https://junglewise.ai/threats/cve-2026-93865-a-missing-authentication-vulnerability-in-the-fireware-os)
- [WatchGuard Fireware OS out-of-bounds read in FireCluster Sync](https://junglewise.ai/threats/cve-2026-93862-an-out-of-bounds-read-vulnerability-in-the-firecluster-sync)
- [WatchGuard Fireware OS stack buffer overflow in SIP proxy](https://junglewise.ai/threats/cve-2026-93857-a-stack-based-buffer-overflow-vulnerability-in-fireware-os-s-sip)
- [WatchGuard Fireware OS XPath injection in SSH authentication](https://junglewise.ai/threats/cve-2026-93434-an-xpath-injection-vulnerability-in-watchguard-fireware-os-s-ssh)