CVE-2021-1879: Apple iOS, iPadOS, and watchOS WebKit Cross-Site Scripting (XSS) Vulnerability

Medium severity, CVSS 6.1. Actively exploited: in CISA KEV since 2021-11-03. EPSS: 7.1% chance of exploitation in the next 30 days.

This issue was addressed by improved management of object lifetimes. This issue is fixed in iOS 12.5.2, iOS 14.4.2 and iPadOS 14.4.2, watchOS 7.3.3. Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue may have been actively exploited..

Affected products

• Apple iPadOS: before 14.4.2 (fixed in 14.4.2)
• Apple iPhone OS: before 12.5.2 (fixed in 12.5.2); from 13.0, before 14.4.2 (fixed in 14.4.2)
• Apple watchOS: before 7.3.3 (fixed in 7.3.3)

Published 2021-04-02. Last modified 2026-06-17.