Key pinning is ignored when overridable errors are encountered — Mozilla

Mozilla security engineer David Keeler reported that when an overridable error is encountered, such as those for expired certificates or a host name does not match a certificate, pinning checks can be be skipped. This would allow for a user to override a pinned certificate when they should not be able to do so. This issue does not allow for third parties to cause a certificate to be overridden and the user would still have to manually do so.