Critical [CVE-2026-93866] integer overflow vulnerability in the WebSocket connection handling used by WatchGuard Fireware OS's Access Portal allows a remote, unauthenticated attacker to write beyond the bounds of a heap buffer by sending a specially crafted request while the Access Portal feature is enabled
This critical-severity WatchGuard advisory covers CVE-2026-93866 affecting Fireware OS.
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Summary
An integer overflow vulnerability in the WebSocket connection handling used by WatchGuard Fireware OS's Access Portal allows a remote, unauthenticated attacker to write beyond the bounds of a heap buffer by sending a specially crafted request while the Access Portal feature is enabled.
- Fireware OS 2025.1 before 2026.4
- Fireware OS 12.0 before 12.12.4
- Fireware OS 12.0 before 12.5.22
Official advisory · high-confidence parse· fetched 1 day ago·verify at source
- 2026.4
- 12.12.4
- 12.5.22
Official advisory · high-confidence parse· fetched 1 day ago·verify at source
Mitigation
Upgrade to a fixed release: 2026.4, 12.12.4, 12.5.22. That is the remediation for this advisory.
The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.
Official advisory · high-confidence parse· fetched 1 day ago·verify at source
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