Safari 26.4 Security Update

What Safari 26.4 Fixes

Safari 26.4, released March 24, 2026, fixes 8 vulnerabilities in 2 parts of the system, according to Apple's security advisory.

Apple does not say that any of them were exploited before the fix. That makes Safari 26.4 a routine security update: worth installing soon, not an emergency.

It has since been superseded: the newest security release for Safari is Safari 27.2, from October 26, 2026, which includes these fixes.

Grouped by us from the impact Apple gives for each fix; the impact lines below are Apple's own.

Which Devices Get Safari 26.4

Apple lists Safari 26.4 for: macOS Sonoma and macOS Sequoia.

How to Install Safari 26.4

Safari updates arrive through Software Update on the Mac. On a current macOS they are part of the macOS update; on older versions they are offered separately.

Security fixes are cumulative: any later release for the same version includes these as well, so if you are already past Safari 26.4 there is nothing to do.

Every Fix in Safari 26.4

All 8 CVEs in Apple's advisory, the most serious kinds first. Each entry is the part of the system affected, Apple's description of the impact and the fix, and the CVE ID.

• WebKit

  A malicious website may be able to process restricted web content outside the sandbox

  The issue was addressed with improved memory handling.

  CVE-2026-28859

• WebKit

  Processing maliciously crafted web content may bypass Same Origin Policy

  A cross-origin issue in the Navigation API was addressed with improved input validation.

  CVE-2026-20643

• WebKit

  Visiting a maliciously crafted website may lead to a cross-site scripting attack

  A logic issue was addressed with improved checks.

  CVE-2026-28871

• WebKit

  Processing maliciously crafted web content may lead to an unexpected process crash

  The issue was addressed with improved memory handling.

  CVE-2026-20664 CVE-2026-28857

• WebKit

  Processing maliciously crafted web content may prevent Content Security Policy from being enforced

  This issue was addressed through improved state management.

  CVE-2026-20665

• WebKit

  A malicious website may be able to access script message handlers intended for other origins

  A logic issue was addressed with improved state management.

  CVE-2026-28861

• WebKit Sandboxing

  A maliciously crafted webpage may be able to fingerprint the user

  An authorization issue was addressed with improved state management.

  CVE-2026-20691

Safari Security Release History

Safari 26.4 in context: the security releases Apple has published for Safari, newest first, with the number of fixes each carried.

The Same Fixes Elsewhere

Apple ships most fixes to every platform that shares the code, and to older versions still under support. These releases close at least one of the same CVEs:

Frequently Asked Questions