CVE-2025-43240: 
Apple Safari vulnerability analysis and mitigation

CVE-2025-43240 is a logic vulnerability discovered in Apple's WebKit engine affecting macOS Sequoia and Safari browsers. The vulnerability was disclosed on July 29, 2025, and fixed in macOS Sequoia 15.6 and Safari 18.6 releases. The issue allows a download's origin to be incorrectly associated, potentially affecting the security of downloaded files (Apple Support, Safari Release).

The vulnerability is classified as a logic issue in WebKit (WebKit Bugzilla: 293994) that was addressed with improved checks. The issue has been assigned a CVSS 3.1 Base Score of 6.2 (MEDIUM) with the vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. The vulnerability is associated with CWE-703 (Improper Check or Handling of Exceptional Conditions) (NVD Database).

The vulnerability could lead to incorrect association of download origins, potentially allowing attackers to bypass security mechanisms that rely on proper origin verification. This could result in users being misled about the source of downloaded files, potentially leading to security risks (Apple Support).

Apple has released patches to address this vulnerability in macOS Sequoia 15.6 and Safari 18.6. Users are advised to update to these versions or later to mitigate the risk. The fix involves improved checks in the WebKit engine to properly handle download origins (Apple Support, Safari Release).