Merge pull request #9950 from Icinga/probot/sync-changelog/support/2.14/9fa41f3b4fbae83d4ca5bbfce4771031b6bd1fa4

CHANGELOG.md: add v2.13.9

Author: Al2Klimov

CHANGELOG.md

@@ -225,6 +225,26 @@ Add `linux_netdev` check command. #9045
 * Several code quality improvements. #8815 #9106 #9250
   #9508 #9517 #9537 #9594 #9605 #9606 #9641 #9658 #9702 #9717 #9738
 
+## 2.13.9 (2023-12-21)
+
+Version 2.13.9 is a hotfix release for masters and satellites that mainly
+prevents permanent disintegration of a whole cluster due to root CA expiry.
+
+### Security
+
+* Automatically renew own root CA and distribute it to all nodes. #9934
+* Update OpenSSL shipped on Windows to v3.0.12. #9945
+* Disable TLS renegotiation (handshake on existing connection). #9945
+
+### Bugfixes
+
+* Icinga DB feature: fix crash due to missing NULL pointer check. #9945
+* Icinga DB feature: fix data written into Redis crashing the Go daemon. #9945
+
+### Updates
+
+* Update Boost shipped on Windows to v1.83. #9945
+
 ## 2.13.8 (2023-07-12)
 
 Version 2.13.8 is a maintenance release that fixes some bugs,