Update CHANGELOG.md for 11.9.3

[ci skip]

CHANGELOG.md

@@ -2,6 +2,20 @@
 documentation](doc/development/changelog.md) for instructions on adding your own
 entry.
 
+## 11.9.3 (2019-03-27)
+
+### Security (8 changes)
+
+- Disallow guest users from accessing Releases.
+- Fix PDF.js vulnerability.
+- Hide "related branches" when user does not have permission.
+- Fix XSS in resolve conflicts form.
+- Added rake task for removing EXIF data from existing uploads.
+- Return cached languages if they've been detected before.
+- Disallow updating namespace when updating a project.
+- Use UntrustedRegexp for matching refs policy.
+
+
 ## 11.9.2 (2019-03-26)
 
 ### Security (8 changes)