Update CHANGELOG.md for 12.1.12

[ci skip]

CHANGELOG.md

@@ -631,6 +631,23 @@ entry.
 - Update Packer.gitlab-ci.yml to use latest image. (Kelly Hair)
 
 
+## 12.1.12
+
+### Security (11 changes)
+
+- Add a policy check for system notes that may not be visible due to cross references to private items.
+- Display only participants that user has permission to see on milestone page.
+- Do not disclose project milestones on group milestones page when project milestones access is disabled in project settings.
+- Fix new project path being disclosed through unsubscribe link of issue/merge requests.
+- Prevent bypassing email verification using Salesforce.
+- Do not show resource label events referencing not accessible labels.
+- Cancel all running CI jobs triggered by the user who is just blocked.
+- Fix Gitaly SearchBlobs flag RPC injection.
+- Only render fixed number of mermaid blocks.
+- Prevent GitLab accounts takeover if SAML is configured.
+- Upgrade mermaid to prevent XSS.
+
+
 ## 12.1.10
 
 - No changes.