Site Isolation Vulnerability in Firefox Navigation Component

CVE-2026-84140

What is CVE-2026-84140?

A site isolation vulnerability has been identified in the DOM navigation component of Firefox, allowing unintended access to cross-origin resources. This issue has implications for user security and data integrity, highlighting the importance of robust browser security practices. Mozilla has released fixes in Firefox version 155 and Firefox ESR 153.2 to mitigate these risks. Users are strongly encouraged to update to the latest versions to ensure their browsing experience remains secure.

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