Update changelog for 16.6.4

[ci skip]

CHANGELOG.md

@@ -922,6 +922,20 @@ entry.
 - [Move export buttons next to each other](gitlab-org/gitlab@106bea7a6246cd153cf66d133936a09d46369ae3) ([merge request](gitlab-org/gitlab!137461))
+## 16.6.4 (2024-01-10)
+
+### Fixed (1 change)
+
+- [Add missing ci_sources_pipelines indexes for self-host](gitlab-org/security/gitlab@3c1411f3e5843e0d52315237b8fcc7d33c7dff2e) ([merge request](gitlab-org/security/gitlab!3810))
+
+### Security (5 changes)
+
+- [Consider older commits when resetting codeowner approvals](gitlab-org/security/gitlab@950b435ea484bcff31bd549d11738ff54fe21ccf) ([merge request](gitlab-org/security/gitlab!3765))
+- [Password reset followups](gitlab-org/security/gitlab@db6b903bac7435dc2484bb4b97715d05a81d45c6) ([merge request](gitlab-org/security/gitlab!3778))
+- [Add verification layer for BaseSlash commands](gitlab-org/security/gitlab@0db0cb8673d406e0f464fd9f6b95e46c3b4f9695) ([merge request](gitlab-org/security/gitlab!3757))
+- [Ensure workspaces are created under same root namespace as agent](gitlab-org/security/gitlab@9d9a33b8201ccd5734ec56b149841193f4611741) ([merge request](gitlab-org/security/gitlab!3760))
+- [Sync security with canonical for 16.6 stable branch](gitlab-org/security/gitlab@e1ec9524344f469375e40145e78d3068462bed05) ([merge request](gitlab-org/security/gitlab!3782))
+
 ## 16.6.2 (2023-12-13)
 ### Fixed (1 change)