Added RELEASE entry

Author: bmribler

release_docs/RELEASE.txt

@@ -751,6 +751,15 @@ Bug Fixes since HDF5-2.0.0 release
 ===================================
     Library
     -------
+    - Fixed CVE 2025 2926
+
+      An image size was corrupted and decoded as 0 resulting in a NULL image
+      buffer, which caused a NULL pointer dereference when the image being
+      copied to the buffer.  The invalid size is now caught and this security
+      vulnerability is prevented.
+
+      Fixes GitHub issue #5384
+
     - Fixed CVE-2025-6269
 
       There were several security vulnerabilities found in the function