CVE-2020-6806: 
NixOS vulnerability analysis and mitigation

CVE-2020-6806 is a security vulnerability discovered in Mozilla Firefox and Thunderbird browsers that was disclosed on March 10, 2020. The vulnerability affects Thunderbird < 68.6, Firefox < 74, Firefox < ESR68.6, and Firefox ESR < 68.6. The issue was discovered by Sergei Glazunov of Google Project Zero (Mozilla Advisory).

The vulnerability occurs when carefully crafting promise resolutions, which could cause an out-of-bounds read off the end of an array resized during script execution. The issue stems from BodyStream::OnInputStreamReady missing protections against state confusion. The vulnerability has a CVSS v3.1 base score of 8.8 (HIGH) with vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (NVD).

This vulnerability could lead to memory corruption and a potentially exploitable crash. The out-of-bounds read could allow attackers to access data beyond the intended array boundaries, potentially leading to information disclosure or arbitrary code execution (Mozilla Advisory).

The vulnerability was fixed in Firefox 74, Firefox ESR 68.6, and Thunderbird 68.6. Users are advised to update to these versions or later to mitigate the risk. The fix involves adding proper protections against state confusion in BodyStream::OnInputStreamReady (Ubuntu Advisory).