What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2021-11-03
• EPSS: 7.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-04-02 · updated 2026-06-17
• Weakness: CWE-79

Description

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; from 13.0 before 14.4.2 — fixed in 12.5.2, 14.4.2
• Apple watchOS: before 7.3.3 — fixed in 7.3.3

How to fix

Upgrade to a fixed version: Apple iPadOS 14.4.2; Apple Iphone Os 12.5.2, 14.4.2; Apple watchOS 7.3.3. Check the vendor advisory for mitigations.

References

• https://support.apple.com/en-us/HT212256
• https://support.apple.com/en-us/HT212257
• https://support.apple.com/en-us/HT212258
• https://support.apple.com/en-us/HT212256
• https://support.apple.com/en-us/HT212257
• https://support.apple.com/en-us/HT212258
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1879

Get alerted when CVE-2021-1879 or the next vulnerability affects your stack