# CVE-2026-86131 — WatchGuard Fireware OS

> As of 2026-10-01, CVE-2026-86131 is a Critical-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in WatchGuard Fireware OS, CVSS v4.0 9.2, EPSS 0.3% (24.0th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-86131, most recently “WatchGuard Fireware OS Critical Code Injection Vulnerability in BOVPN over TLS Client (CVE-2026-86131)”.

**Last updated:** 2026-10-01

## What is CVE-2026-86131?

A code injection vulnerability in WatchGuard Fireware OS's BOVPN Over TLS client configuration handling allows an attacker who controls the remote VPN server to execute arbitrary commands as root on the connecting Firebox.

The record classifies CVE-2026-86131 under weakness classes [CWE-295](https://intel.threadlinqs.com/cwe/CWE-295), [CWE-829](https://intel.threadlinqs.com/cwe/CWE-829), [CWE-94](https://intel.threadlinqs.com/cwe/CWE-94). 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 6 days ago.

## Severity and exploitation probability

- **CVSS v4.0 base score:** 9.2 — Critical (derived from score) (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 24.0% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-29, last modified 2026-10-01

## Is CVE-2026-86131 being exploited?

No public exploitation evidence for CVE-2026-86131 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-10-01. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.

## Affected products and versions

- [WatchGuard](https://intel.threadlinqs.com/vendors/watchguard): Fireware OS

## How to fix CVE-2026-86131

No vendor patch reference has been recorded for CVE-2026-86131 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-86131

1 tracked threat in the Threadlinqs corpus references CVE-2026-86131, either in the campaign’s CVE list or as an indicator on the campaign record.

- [WatchGuard Fireware OS Critical Code Injection Vulnerability in BOVPN over TLS Client (CVE-2026-86131)](https://intel.threadlinqs.com/threat/TL-2026-2813) — CRITICAL · 2026-09-30

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-10-02. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [psirt.watchguard.com — vendor advisory](https://psirt.watchguard.com/CVE-2026-86131)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-86131
Full detection coverage and IOCs for threats exploiting CVE-2026-86131 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp