diff --git a/output/openapi/elasticsearch-openapi.json b/output/openapi/elasticsearch-openapi.json
index d49ea162ac..4f237244ed 100644
--- a/output/openapi/elasticsearch-openapi.json
+++ b/output/openapi/elasticsearch-openapi.json
@@ -81996,10 +81996,17 @@
           },
           "names": {
             "description": "A list of indices (or index name patterns) to which the permissions in this entry apply.",
-            "type": "array",
-            "items": {
-              "$ref": "#/components/schemas/_types:IndexName"
-            }
+            "oneOf": [
+              {
+                "$ref": "#/components/schemas/_types:IndexName"
+              },
+              {
+                "type": "array",
+                "items": {
+                  "$ref": "#/components/schemas/_types:IndexName"
+                }
+              }
+            ]
           },
           "privileges": {
             "description": "The index level privileges that owners of the role have on the specified indices.",
@@ -82136,10 +82143,17 @@
           },
           "names": {
             "description": "A list of indices (or index name patterns) to which the permissions in this entry apply.",
-            "type": "array",
-            "items": {
-              "$ref": "#/components/schemas/_types:IndexName"
-            }
+            "oneOf": [
+              {
+                "$ref": "#/components/schemas/_types:IndexName"
+              },
+              {
+                "type": "array",
+                "items": {
+                  "$ref": "#/components/schemas/_types:IndexName"
+                }
+              }
+            ]
           },
           "privileges": {
             "description": "The index level privileges that owners of the role have on the specified indices.",
@@ -82342,10 +82356,17 @@
         "properties": {
           "names": {
             "description": "A list of indices (or index name patterns) to which the permissions in this entry apply.",
-            "type": "array",
-            "items": {
-              "$ref": "#/components/schemas/_types:IndexName"
-            }
+            "oneOf": [
+              {
+                "$ref": "#/components/schemas/_types:IndexName"
+              },
+              {
+                "type": "array",
+                "items": {
+                  "$ref": "#/components/schemas/_types:IndexName"
+                }
+              }
+            ]
           },
           "allow_restricted_indices": {
             "description": "This needs to be set to true if the patterns in the names field should cover system indices.",
@@ -82364,10 +82385,17 @@
           },
           "names": {
             "description": "A list of indices (or index name patterns) to which the permissions in this entry apply.",
-            "type": "array",
-            "items": {
-              "$ref": "#/components/schemas/_types:IndexName"
-            }
+            "oneOf": [
+              {
+                "$ref": "#/components/schemas/_types:IndexName"
+              },
+              {
+                "type": "array",
+                "items": {
+                  "$ref": "#/components/schemas/_types:IndexName"
+                }
+              }
+            ]
           },
           "query": {
             "$ref": "#/components/schemas/security._types:IndicesPrivilegesQuery"
@@ -82869,10 +82897,17 @@
           },
           "names": {
             "description": "A list of indices (or index name patterns) to which the permissions in this entry apply.",
-            "type": "array",
-            "items": {
-              "$ref": "#/components/schemas/_types:IndexName"
-            }
+            "oneOf": [
+              {
+                "$ref": "#/components/schemas/_types:IndexName"
+              },
+              {
+                "type": "array",
+                "items": {
+                  "$ref": "#/components/schemas/_types:IndexName"
+                }
+              }
+            ]
           },
           "privileges": {
             "description": "The index level privileges that owners of the role have on the specified indices.",
diff --git a/output/openapi/elasticsearch-serverless-openapi.json b/output/openapi/elasticsearch-serverless-openapi.json
index 261d6563c3..6fbd28e689 100644
--- a/output/openapi/elasticsearch-serverless-openapi.json
+++ b/output/openapi/elasticsearch-serverless-openapi.json
@@ -53722,10 +53722,17 @@
           },
           "names": {
             "description": "A list of indices (or index name patterns) to which the permissions in this entry apply.",
-            "type": "array",
-            "items": {
-              "$ref": "#/components/schemas/_types:IndexName"
-            }
+            "oneOf": [
+              {
+                "$ref": "#/components/schemas/_types:IndexName"
+              },
+              {
+                "type": "array",
+                "items": {
+                  "$ref": "#/components/schemas/_types:IndexName"
+                }
+              }
+            ]
           },
           "privileges": {
             "description": "The index level privileges that owners of the role have on the specified indices.",
diff --git a/output/schema/schema-serverless.json b/output/schema/schema-serverless.json
index 3a97ce424f..47a1b2cbed 100644
--- a/output/schema/schema-serverless.json
+++ b/output/schema/schema-serverless.json
@@ -103066,7 +103066,7 @@
         "name": "IndexPrivilege",
         "namespace": "security._types"
       },
-      "specLocation": "security/_types/Privileges.ts#L360-L402"
+      "specLocation": "security/_types/Privileges.ts#L362-L404"
     },
     {
       "codegenNames": [
@@ -103080,7 +103080,7 @@
         "name": "IndicesPrivilegesQuery",
         "namespace": "security._types"
       },
-      "specLocation": "security/_types/Privileges.ts#L315-L323",
+      "specLocation": "security/_types/Privileges.ts#L317-L325",
       "type": {
         "items": [
           {
@@ -103130,7 +103130,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L325-L335"
+      "specLocation": "security/_types/Privileges.ts#L327-L337"
     },
     {
       "kind": "interface",
@@ -103218,7 +103218,7 @@
         }
       ],
       "shortcutProperty": "source",
-      "specLocation": "security/_types/Privileges.ts#L337-L355"
+      "specLocation": "security/_types/Privileges.ts#L339-L357"
     },
     {
       "codegenNames": [
@@ -103230,7 +103230,7 @@
         "name": "RoleTemplateInlineQuery",
         "namespace": "security._types"
       },
-      "specLocation": "security/_types/Privileges.ts#L357-L358",
+      "specLocation": "security/_types/Privileges.ts#L359-L360",
       "type": {
         "items": [
           {
@@ -139723,14 +139723,26 @@
           "name": "names",
           "required": true,
           "type": {
-            "kind": "array_of",
-            "value": {
-              "kind": "instance_of",
-              "type": {
-                "name": "IndexName",
-                "namespace": "_types"
+            "items": [
+              {
+                "kind": "instance_of",
+                "type": {
+                  "name": "IndexName",
+                  "namespace": "_types"
+                }
+              },
+              {
+                "kind": "array_of",
+                "value": {
+                  "kind": "instance_of",
+                  "type": {
+                    "name": "IndexName",
+                    "namespace": "_types"
+                  }
+                }
               }
-            }
+            ],
+            "kind": "union_of"
           }
         },
         {
@@ -139761,7 +139773,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L217-L241"
+      "specLocation": "security/_types/Privileges.ts#L217-L243"
     },
     {
       "kind": "interface",
diff --git a/output/schema/schema.json b/output/schema/schema.json
index 7aba15d81b..651fe95def 100644
--- a/output/schema/schema.json
+++ b/output/schema/schema.json
@@ -187078,7 +187078,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L408-L410"
+      "specLocation": "security/_types/Privileges.ts#L410-L412"
     },
     {
       "kind": "interface",
@@ -187603,7 +187603,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L404-L406"
+      "specLocation": "security/_types/Privileges.ts#L406-L408"
     },
     {
       "kind": "enum",
@@ -187716,7 +187716,7 @@
         "name": "IndexPrivilege",
         "namespace": "security._types"
       },
-      "specLocation": "security/_types/Privileges.ts#L360-L402"
+      "specLocation": "security/_types/Privileges.ts#L362-L404"
     },
     {
       "kind": "interface",
@@ -187744,14 +187744,26 @@
           "name": "names",
           "required": true,
           "type": {
-            "kind": "array_of",
-            "value": {
-              "kind": "instance_of",
-              "type": {
-                "name": "IndexName",
-                "namespace": "_types"
+            "kind": "union_of",
+            "items": [
+              {
+                "kind": "instance_of",
+                "type": {
+                  "name": "IndexName",
+                  "namespace": "_types"
+                }
+              },
+              {
+                "kind": "array_of",
+                "value": {
+                  "kind": "instance_of",
+                  "type": {
+                    "name": "IndexName",
+                    "namespace": "_types"
+                  }
+                }
               }
-            }
+            ]
           }
         },
         {
@@ -187798,7 +187810,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L217-L241"
+      "specLocation": "security/_types/Privileges.ts#L217-L243"
     },
     {
       "kind": "type_alias",
@@ -187812,7 +187824,7 @@
         "name": "IndicesPrivilegesQuery",
         "namespace": "security._types"
       },
-      "specLocation": "security/_types/Privileges.ts#L315-L323",
+      "specLocation": "security/_types/Privileges.ts#L317-L325",
       "type": {
         "kind": "union_of",
         "items": [
@@ -187862,7 +187874,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L412-L414"
+      "specLocation": "security/_types/Privileges.ts#L414-L416"
     },
     {
       "kind": "interface",
@@ -187958,7 +187970,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L277-L289"
+      "specLocation": "security/_types/Privileges.ts#L279-L291"
     },
     {
       "kind": "interface",
@@ -187999,14 +188011,26 @@
           "name": "names",
           "required": true,
           "type": {
-            "kind": "array_of",
-            "value": {
-              "kind": "instance_of",
-              "type": {
-                "name": "IndexName",
-                "namespace": "_types"
+            "kind": "union_of",
+            "items": [
+              {
+                "kind": "instance_of",
+                "type": {
+                  "name": "IndexName",
+                  "namespace": "_types"
+                }
+              },
+              {
+                "kind": "array_of",
+                "value": {
+                  "kind": "instance_of",
+                  "type": {
+                    "name": "IndexName",
+                    "namespace": "_types"
+                  }
+                }
               }
-            }
+            ]
           }
         },
         {
@@ -188053,7 +188077,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L243-L275"
+      "specLocation": "security/_types/Privileges.ts#L245-L277"
     },
     {
       "kind": "interface",
@@ -188067,14 +188091,26 @@
           "name": "names",
           "required": true,
           "type": {
-            "kind": "array_of",
-            "value": {
-              "kind": "instance_of",
-              "type": {
-                "name": "IndexName",
-                "namespace": "_types"
+            "kind": "union_of",
+            "items": [
+              {
+                "kind": "instance_of",
+                "type": {
+                  "name": "IndexName",
+                  "namespace": "_types"
+                }
+              },
+              {
+                "kind": "array_of",
+                "value": {
+                  "kind": "instance_of",
+                  "type": {
+                    "name": "IndexName",
+                    "namespace": "_types"
+                  }
+                }
               }
-            }
+            ]
           }
         },
         {
@@ -188091,7 +188127,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L416-L426"
+      "specLocation": "security/_types/Privileges.ts#L418-L428"
     },
     {
       "kind": "interface",
@@ -188663,7 +188699,7 @@
         "name": "RoleTemplateInlineQuery",
         "namespace": "security._types"
       },
-      "specLocation": "security/_types/Privileges.ts#L357-L358",
+      "specLocation": "security/_types/Privileges.ts#L359-L360",
       "type": {
         "kind": "union_of",
         "items": [
@@ -188706,7 +188742,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L325-L335"
+      "specLocation": "security/_types/Privileges.ts#L327-L337"
     },
     {
       "kind": "interface",
@@ -188794,7 +188830,7 @@
         }
       ],
       "shortcutProperty": "source",
-      "specLocation": "security/_types/Privileges.ts#L337-L355"
+      "specLocation": "security/_types/Privileges.ts#L339-L357"
     },
     {
       "kind": "interface",
@@ -188822,14 +188858,26 @@
           "name": "names",
           "required": true,
           "type": {
-            "kind": "array_of",
-            "value": {
-              "kind": "instance_of",
-              "type": {
-                "name": "IndexName",
-                "namespace": "_types"
+            "kind": "union_of",
+            "items": [
+              {
+                "kind": "instance_of",
+                "type": {
+                  "name": "IndexName",
+                  "namespace": "_types"
+                }
+              },
+              {
+                "kind": "array_of",
+                "value": {
+                  "kind": "instance_of",
+                  "type": {
+                    "name": "IndexName",
+                    "namespace": "_types"
+                  }
+                }
               }
-            }
+            ]
           }
         },
         {
@@ -188861,7 +188909,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L428-L448"
+      "specLocation": "security/_types/Privileges.ts#L430-L450"
     },
     {
       "kind": "enum",
@@ -189022,14 +189070,26 @@
           "name": "names",
           "required": true,
           "type": {
-            "kind": "array_of",
-            "value": {
-              "kind": "instance_of",
-              "type": {
-                "name": "IndexName",
-                "namespace": "_types"
+            "kind": "union_of",
+            "items": [
+              {
+                "kind": "instance_of",
+                "type": {
+                  "name": "IndexName",
+                  "namespace": "_types"
+                }
+              },
+              {
+                "kind": "array_of",
+                "value": {
+                  "kind": "instance_of",
+                  "type": {
+                    "name": "IndexName",
+                    "namespace": "_types"
+                  }
+                }
               }
-            }
+            ]
           }
         },
         {
@@ -189075,7 +189135,7 @@
           }
         }
       ],
-      "specLocation": "security/_types/Privileges.ts#L291-L313"
+      "specLocation": "security/_types/Privileges.ts#L293-L315"
     },
     {
       "kind": "interface",
diff --git a/output/typescript/types.ts b/output/typescript/types.ts
index 1d952fa3ac..0b40137e2c 100644
--- a/output/typescript/types.ts
+++ b/output/typescript/types.ts
@@ -17668,7 +17668,7 @@ export type SecurityIndexPrivilege = 'all' | 'auto_configure' | 'create' | 'crea
 
 export interface SecurityIndicesPrivileges {
   field_security?: SecurityFieldSecurity
-  names: IndexName[]
+  names: IndexName | IndexName[]
   privileges: SecurityIndexPrivilege[]
   query?: SecurityIndicesPrivilegesQuery
   allow_restricted_indices?: boolean
@@ -17695,14 +17695,14 @@ export interface SecurityRemoteClusterPrivileges {
 export interface SecurityRemoteIndicesPrivileges {
   clusters: Names
   field_security?: SecurityFieldSecurity
-  names: IndexName[]
+  names: IndexName | IndexName[]
   privileges: SecurityIndexPrivilege[]
   query?: SecurityIndicesPrivilegesQuery
   allow_restricted_indices?: boolean
 }
 
 export interface SecurityReplicationAccess {
-  names: IndexName[]
+  names: IndexName | IndexName[]
   allow_restricted_indices?: boolean
 }
 
@@ -17770,7 +17770,7 @@ export interface SecurityRoleTemplateScript {
 
 export interface SecuritySearchAccess {
   field_security?: SecurityFieldSecurity
-  names: IndexName[]
+  names: IndexName | IndexName[]
   query?: SecurityIndicesPrivilegesQuery
   allow_restricted_indices?: boolean
 }
@@ -17789,7 +17789,7 @@ export interface SecurityUser {
 
 export interface SecurityUserIndicesPrivileges {
   field_security?: SecurityFieldSecurity[]
-  names: IndexName[]
+  names: IndexName | IndexName[]
   privileges: SecurityIndexPrivilege[]
   query?: SecurityIndicesPrivilegesQuery[]
   allow_restricted_indices: boolean
diff --git a/specification/security/_types/Privileges.ts b/specification/security/_types/Privileges.ts
index b7ee5bcf81..6836f8494e 100644
--- a/specification/security/_types/Privileges.ts
+++ b/specification/security/_types/Privileges.ts
@@ -220,10 +220,12 @@ export class IndicesPrivileges {
    * @doc_id field-and-document-access-control
    */
   field_security?: FieldSecurity
+  // We're using IndexName | IndexName[] instead of Indices in this file on purpose:
+  // https://github.com/elastic/elasticsearch-specification/pull/3127
   /**
    * A list of indices (or index name patterns) to which the permissions in this entry apply.
    */
-  names: IndexName[]
+  names: IndexName | IndexName[]
   /**
    * The index level privileges that owners of the role have on the specified indices.
    */
@@ -257,7 +259,7 @@ export class RemoteIndicesPrivileges {
   /**
    * A list of indices (or index name patterns) to which the permissions in this entry apply.
    */
-  names: IndexName[]
+  names: IndexName | IndexName[]
   /**
    * The index level privileges that owners of the role have on the specified indices.
    */
@@ -297,7 +299,7 @@ export class UserIndicesPrivileges {
   /**
    * A list of indices (or index name patterns) to which the permissions in this entry apply.
    */
-  names: IndexName[]
+  names: IndexName | IndexName[]
   /**
    * The index level privileges that owners of the role have on the specified indices.
    */
@@ -417,7 +419,7 @@ export class ReplicationAccess {
   /**
    * A list of indices (or index name patterns) to which the permissions in this entry apply.
    */
-  names: IndexName[]
+  names: IndexName | IndexName[]
   /**
    * This needs to be set to true if the patterns in the names field should cover system indices.
    * @server_default false
@@ -434,7 +436,7 @@ export class SearchAccess {
   /**
    * A list of indices (or index name patterns) to which the permissions in this entry apply.
    */
-  names: IndexName[]
+  names: IndexName | IndexName[]
   /**
    * A search query that defines the documents the owners of the role have access to. A document within the specified indices must match this query for it to be accessible by the owners of the role.
    */