---
id: "CVE-2021-30665"
kind: "vulnerability"
aliases: ["CVE-2021-30665"]
title: "Apple Multiple Products: Apple Multiple Products WebKit Memory Corruption Vulnerability"
severity: "high"
cvss: 8.8
epss: 0.03706
exploited: true
status: "open"
category: "vendor"
products: [{"name": "Apple Multiple Products", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["apple", "exploited", "ios", "macos", "safari", "vendor", "webkit"]
not_affected_if: ["unpatched-builds-only"]
published_at: "2021-09-08T15:15:13+00:00"
first_seen_at: "2026-10-23T19:11:53+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-2021-30665", "first_seen_at": "2026-10-23T19:11:53+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2021-30665", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-30665", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Apple Multiple Products: Apple Multiple Products WebKit Memory Corruption Vulnerability

A memory corruption bug in Apple's WebKit engine lets a crafted web page run code when it is processed. It is listed as exploited in the wild, so attackers have used it.

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

## Affected

- vendor:Apple Multiple Products affected ? fixed ?

## Fix

Update iOS, iPadOS, macOS, watchOS and tvOS to a patched Apple release per vendor instructions. Fixed versions are not stated in the sources.

## Timeline

- 2026-10-23T19:11:53+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-30665
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2021-30665
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2021-30665

## From the sources

Apple iOS, iPadOS, macOS, watchOS, and tvOS WebKit contain a memory corruption vulnerability that leads to code execution when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

CISA required action: Apply updates per vendor instructions.

---

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