Browser isolation and memory handling received security fixes in Firefox 158, according to Mozilla's October 13 advisory. The release addresses high-impact issues across networking, storage, graphics and the application-update component.
A browser's sandbox limits what a compromised component can reach. Site isolation adds boundaries between web content. Weaknesses in those boundaries matter because a problem in one part of the browser should not automatically expose everything else.
The advisory lists several networking issues involving sandbox escapes and incorrect boundary conditions. It also identifies use-after-free errors, where software tries to use memory after releasing it. These appear in networking, IndexedDB storage and graphics components.
Another listed issue concerns privilege escalation in the update component. Mozilla marks the overall advisory as high impact and identifies Firefox 158 as the fixed version.
These entries describe software defects and their fixes. The advisory is not evidence that every listed flaw was used against people in the wild, and it does not establish a single attack joining them together.
Mozilla has also changed its reporting format. Instead of grouping internally found memory-safety problems under one vulnerability identifier, it now issues an advisory entry for each individual bug.
That means the number of identifiers alone is a poor measure of whether one release is less secure than another. A changed reporting practice can increase the count without a corresponding increase in real-world incidents.
The relevant release boundary is explicit in Mozilla's notice. The listed fixes are in Firefox 158.
