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CVE-2021-1789

High CVSS 8.8 Known exploited

Published 2021-04-02 · last changed 2026-06-17 · added to CISA KEV 2022-05-04

This one is being exploited in the wild.

CISA added CVE-2021-1789 to the Known Exploited Vulnerabilities catalog on 2022-05-04. 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-2021-1789, 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

A type confusion issue was addressed with improved state handling. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, tvOS 14.4, watchOS 7.3, iOS 14.4 and iPadOS 14.4, Safari 14.0.3. Processing maliciously crafted web content may lead to arbitrary code execution.

Sources

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