CVE-2020-15652: Canonical Ubuntu Linux

Medium severity, CVSS 6.5. EPSS: 1.3% chance of exploitation in the next 30 days.

By observing the stack trace for JavaScript errors in web workers, it was possible to leak the result of a cross-origin redirect. This applied only to content that can be parsed as script. This vulnerability affects Firefox < 79, Firefox ESR < 68.11, Firefox ESR < 78.1, Thunderbird < 68.11, 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); from 78.0, before 78.1 (fixed in 78.1)
• Mozilla Firefox ESR: before 68.11 (fixed in 68.11)
• Mozilla Thunderbird: before 68.11 (fixed in 68.11); from 78.0, before 78.1 (fixed in 78.1)

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