When recursing through graphical layers while scrolling, an iterator may have become invalid, resulting in a potential use-after-free. This occurs because the function APZCTreeManager::ComputeClippedCompositionBounds did not follow invalidation rules. This vulnerability affects Firefox < 81, Thunderbird < 78.3, and Firefox ESR <78.3. The vulnerability has been modified since it was last analyzed by the NVD. It is awaiting reanalysis which may result in further changes to the information provided."] Source: https://nvd.nist.gov/vuln/detail/CVE-2020-15678