CVE-2020-26976
Mozilla: HTTPS pages could have been intercepted by a registered service worker when they should not have been
Severity
ModerateRed Hat Product Security
CVSS 3.0
Review impact separately from score.
Published · January 26, 2021
Updated · November 22, 2025
Description
The Mozilla Foundation Security Advisory describes this flaw as:
When a HTTPS page was embedded in a HTTP page, and there was a service worker registered for the former, the service worker could have intercepted the request for the secure page despite the iframe not being a secure context due to the (insecure) framing.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
No mitigation is specified in collected source.
CVSS / CWE
CVSS 3.0 · 6.1CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor