Release notes for 2.1.9, 2.4.3, 2.5.5, 2.6.1, 2.7

Change-Id: I80c76a9bb20030922ca9e6a100e282cc4a18b12e
diff --git a/ReleaseNotes/ReleaseNotes-2.4.3.txt b/ReleaseNotes/ReleaseNotes-2.4.3.txt
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+Release notes for Gerrit 2.4.3
+==============================
+
+There are no schema changes from link:ReleaseNotes-2.4.2.html[2.4.2].
+
+link:https://gerrit-releases.storage.googleapis.com/gerrit-2.4.3.war[https://gerrit-releases.storage.googleapis.com/gerrit-2.4.3.war]
+
+Bug Fixes
+---------
+* Patch JGit security hole
++
+The security hole may permit a modified Git client to gain access
+to hidden or deleted branches if the user has read permission on
+at least one branch in the repository. Access requires knowing a
+SHA-1 to request, which may be discovered out-of-band from an issue
+tracker or gitweb instance.