Heap buffer overflow
A write runs past allocated heap storage and can damage neighbouring data.
CWE-122 · CISA KEV
Video course · Free course. C programming and memory concepts are useful; covers several weakness types.
Exploited. On CISA's list since 2022-03-25.
WatchGuard Firebox and XTM Appliances Arbitrary Code Execution
CVE-2022-26318 · WatchGuard Firebox and XTM Appliances · Published 2022-03-04
How bad would it be?
9.8 out of 10
CVSS rates it critical: about as damaging as flaws get.
How likely is it to be used?
78%
Estimated chance of exploitation in the next 30 days, among the top 1% of all scored flaws (EPSS, 2026-10-29).
Is it already being used?
Yes
CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 1659 days ago (2022-04-15).
What CISA says to do
Apply updates per vendor instructions.
On WatchGuard Firebox and XTM appliances, an unauthenticated user can execute arbitrary code.
What the flaw is
On WatchGuard Firebox and XTM appliances, an unauthenticated user can execute arbitrary code, aka FBX-22786. This vulnerability impacts Fireware OS before 12.7.2_U2, 12.x before 12.1.3_U8, and 12.2.x through 12.5.x before 12.5.9_U2.
From the NVD.
Fixes and advisories
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Explore this week’s weaknesses and all learning topics
Understand the kind of weakness behind this flaw. These resources teach the weakness, rather than reproduce this specific CVE. Follow the vendor's advice above to fix the affected product.
CWE is a catalogue of weakness types. Labels come from the sources shown and can differ or change. Resource matches reviewed 16 October 2026.
On SentryFeed
No story in the last 14 days has mentioned it.
Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.