CVE-2020-12415: Mozilla Firefox

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

When "%2F" was present in a manifest URL, Firefox's AppCache behavior may have become confused and allowed a manifest to be served from a subdirectory. This could cause the appcache to be used to service requests for the top level directory. This vulnerability affects Firefox < 78.

Affected products

• Mozilla Firefox: before 78.0 (fixed in 78.0)
• Opensuse Leap: version 15.1 only; version 15.2 only

Published 2020-07-09. Last modified 2026-06-17.