Apple · iOS, iPadOS, and watchOS
CVE-2021-1879
Apple iOS, iPadOS, and watchOS WebKit Cross-Site Scripting (XSS) Vulnerability
What it is
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..
CISA: Apple iOS, iPadOS, and watchOS WebKit contain an unspecified vulnerability that allows for universal cross-site scripting (XSS) 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.
What to do
Apply updates per vendor instructions.
Deadline for US federal agencies: November 17, 2021
More exploited flaws from Apple
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Sep 11, 2023 | Wallet Code Execution | iOS, iPadOS, and watchOS | High 7.8 | 4.4% |
| Nov 3, 2021 | Out-of-Bounds Write | iOS, iPadOS, and watchOS | High 8.8 | 2.3% |
| Nov 3, 2021 | Memory Corruption | iOS, iPadOS, and watchOS | Medium 4.3 | 2.2% |
| Sep 29, 2026 | Out-of-Bounds Write | Multiple Products | High 8.8 | 26% |
| Aug 18, 2026 | Improper Authentication | macOS | Critical 9.8 | 1.7% |
| Mar 20, 2026 | Buffer Overflow | Multiple Products | High 8.8 | 1.7% |
| Mar 20, 2026 | Improper Locking | Multiple Products | High 7.8 | 0.4% |
| Mar 20, 2026 | Classic Buffer Overflow | Multiple Products | Medium 5.5 | 0.4% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.