---
id: "CVE-2021-1789"
kind: "vulnerability"
aliases: ["CVE-2021-1789"]
title: "Apple Multiple Products: Apple Multiple Products Type Confusion Vulnerability"
severity: "high"
cvss: 8.8
epss: 0.13975
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Apple Multiple Products", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["apple", "exploited", "infrastructure", "ios", "macos", "safari", "webkit"]
not_affected_if: ["fully-patched-devices"]
published_at: "2021-04-02T18:15:21+00:00"
first_seen_at: "2026-10-23T19:11:52+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-1789", "first_seen_at": "2026-10-23T19:11:52+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2021-1789", "first_seen_at": "2026-10-23T19:13:45+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-1789", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Apple Multiple Products: Apple Multiple Products Type Confusion Vulnerability

A type confusion bug in WebKit-based Apple products lets crafted web content trigger memory corruption. An attacker who gets a victim to load a malicious page can run arbitrary code on the device.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Apple Multiple Products affected ? fixed ?

## Fix

Update Apple devices and software to the vendor-fixed release per Apple's advisory; the sources do not give the version.

## Timeline

- 2026-10-23T19:11:52+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-1789
- 2026-10-23T19:13:45+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2021-1789
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2021-1789

## From the sources

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.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_