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CVE-2020-9818

High CVSS 8.8 Known exploited

Published 2020-06-09 · last changed 2026-06-17 · added to CISA KEV 2021-11-03

This one is being exploited in the wild.

CISA added CVE-2020-9818 to the Known Exploited Vulnerabilities catalog on 2021-11-03. Federal agencies are required to remediate it on a deadline. If you have affected machines, this is the class of finding that moves ahead of the rest of the queue.

The fix

We hold no Microsoft remediation data for CVE-2020-9818, which normally means it is not a Windows CVE. For non-Microsoft software the fix is the vendor's own updated release, and the affected versions are listed below.

What it is

An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.

Sources

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H