Security/Features/Cert Blocklist via Update Ping

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Cert Blocklist via Update Ping
Stage On hold
Status In progress
Release target `
Health OK
Status note `


Product manager Sid Stamm
Directly Responsible Individual David Keeler
Lead engineer David Keeler
Security lead Curtis Koenig
Privacy lead Sid Stamm
Localization lead `
Accessibility lead `
QA lead `
UX lead `
Product marketing lead `
Operations lead `
Additional members `

Open issues/risks

The general blocklisting mechanism currently in Firefox is potentially being redesigned. As the simplest way to implement this feature is to piggyback on the blocklist, any changes to that mechanism will have to be taken into consideration. See

Stage 1: Definition

1. Feature overview

This feature is a subscription-based blocklisting of certs via update ping. It allows Mozilla to push out rapid blocklist of certificates when something bad happens in the PKI infrastructure. This prevents us from having to ship an update to disable a root or block a certificate.

2. Users & use cases

There are currently three use cases this feature addresses:

  • A CA is no longer trusted (in its entirety)
  • A CA's intermediate certificate is no longer trusted
  • The key of an end-entity certificate belonging to a high-profile entity is compromised (e.g. a bank, government, etc.)

Instead of spinning up and releasing a binary update, we simply add entries as appropriate to the blocklist. Next time the user's browser pings us for updates, we ship them the new blocklist and the changes instantly take effect.

3. Dependencies


4. Requirements

  • The ability to block root certificates, intermediate certificates, and end-entity certificates
  • The ability to block certificates using specific keys
  • The ability to undo a block should one be applied erroneously


This will not serve the same purpose as shipping a white-list of all intermediate certificates, which is another proposal under discussion. In theory, once that feature is realized, only end-entity entries will be put on the blocklist and CA intermediate or root certs can simply be removed from the white-list.

This does not solve revocation in general. We will not add Joe Schmoe's compromised server certificate to the blocklist.

Stage 2: Design

5. Functional specification


6. User experience design

There should not be any UX changes.

Stage 3: Planning

7. Implementation plan


8. Reviews

Security review


Privacy review


Localization review




Quality Assurance review


Operations review


Stage 4: Development

9. Implementation


Stage 5: Release

10. Landing criteria


Feature details

Priority P2
Rank 999
Theme / Goal Product Hardening
Roadmap Security
Secondary roadmap Platform
Feature list `
Project `
Engineering team Security

Team status notes

  status notes
Products ` `
Engineering ` `
Security ` `
Privacy ` `
Localization ` `
Accessibility ` `
Quality assurance ` `
User experience ` `
Product marketing ` `
Operations ` `