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CVE-2026-8247 — Fireware OS

CVE-2026-8247 is a CWE-120 vulnerability in WatchGuard Fireware OS. A fix is available — see the affected versions and patch details below.

An Out-of-bounds Write vulnerability in WatchGuard Fireware OS may allow an unauthenticated attacker on the same local network segment to execute arbitrary code. This vulnerability…

Published
Updated
Affected
3 products
Patched
See advisory
Exploits
None indexed
Exploitation data as of Nov 13, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-8247.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs33th percentile — riskier than 33% of all scored CVEsHighest risk
0.00%0.29%0.59%0.88%0.2%0.3%0.4%0.4%0.4%Aug 26Oct 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Description

An Out-of-bounds Write vulnerability in WatchGuard Fireware OS may allow an unauthenticated attacker on the same local network segment to execute arbitrary code.

This vulnerability affects Fireware OS 11.0 up to and including 11.12.4_Update1, 12.0 up to and including 12.12 and 2025.1 up to and including 2026.2.

Affected Products

3 products · 3 configurations
Application
Fireware OSWatchGuard
< 2026.2.1
3 versions
2025.112.011.0
Application
Fireware OSWatchGuard
< 12.11.9
1 version
12.0
Application
Fireware OSWatchGuard
< 12.5.19
1 version
12.0

Detection & mitigation playbook

Vendor / appliance

  1. Detect

    Inventory every WatchGuard Fireware OS deployment and check each version against the affected-products list above.

  2. Fix

    Apply the WatchGuard Fireware OS security patch or hotfix for CVE-2026-8247 on the affected version, following the vendor advisory for your exact build.

  3. Workarounds

    Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Frequently Asked Questions

An Out-of-bounds Write vulnerability in WatchGuard Fireware OS may allow an unauthenticated attacker on the same local network segment to execute arbitrary code. This vulnerability affects Fireware OS 11.0 up to and including 11.12.4_Update1, 12.0 up to and including 12.12 and 2025.1 up to and including 2026.2.
O3 Security · Runtime Protection

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CVE-2026-8247: Fireware OS