CVE-2020-15655: Canonical Ubuntu Linux

Medium severity, CVSS 6.5. EPSS: 1.5% chance of exploitation in the next 30 days.

A redirected HTTP request which is observed or modified through a web extension could bypass existing CORS checks, leading to potential disclosure of cross-origin information. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

Affected products

• Canonical Ubuntu Linux: version 16.04 only; version 18.04 only; version 20.04 only
• Mozilla Firefox: before 79.0 (fixed in 79.0)
• Mozilla Firefox ESR: before 78.1 (fixed in 78.1)
• Mozilla Thunderbird: before 78.1 (fixed in 78.1)
• Opensuse Leap: version 15.2 only

Published 2020-08-10. Last modified 2026-06-17.