3 files changed, 30 insertions, 1 deletions
diff --git a/activemodel/CHANGELOG.md b/activemodel/CHANGELOG.md
index 56fbfacbd7..51912ec3ce 100644
--- a/activemodel/CHANGELOG.md
+++ b/activemodel/CHANGELOG.md
@@ -1,3 +1,9 @@
+*   Type cast falsy boolean symbols on boolean attribute as false.
+
+    Fixes #35676.
+
+    *Ryuta Kamizono*
+
 *   Change how validation error translation strings are fetched: The new behavior
     will first try the more specific keys, including doing locale fallback, then try
     the less specific ones.
diff --git a/activemodel/lib/active_model/type/boolean.rb b/activemodel/lib/active_model/type/boolean.rb
index f6c6efbc87..e64d2c793c 100644
--- a/activemodel/lib/active_model/type/boolean.rb
+++ b/activemodel/lib/active_model/type/boolean.rb
@@ -14,7 +14,16 @@ module ActiveModel
     # - Empty strings are coerced to +nil+
     # - All other values will be coerced to +true+
     class Boolean < Value
-      FALSE_VALUES = [false, 0, "0", "f", "F", "false", "FALSE", "off", "OFF"].to_set
+      FALSE_VALUES = [
+        false, 0,
+        "0", :"0",
+        "f", :f,
+        "F", :F,
+        "false", :false,
+        "FALSE", :FALSE,
+        "off", :off,
+        "OFF", :OFF,
+      ].to_set.freeze
 
       def type # :nodoc:
         :boolean
diff --git a/activemodel/test/cases/type/boolean_test.rb b/activemodel/test/cases/type/boolean_test.rb
index 2de0f53640..7f8490b2fe 100644
--- a/activemodel/test/cases/type/boolean_test.rb
+++ b/activemodel/test/cases/type/boolean_test.rb
@@ -23,6 +23,13 @@ module ActiveModel
         assert type.cast("\u3000\r\n")
         assert type.cast("\u0000")
         assert type.cast("SOMETHING RANDOM")
+        assert type.cast(:"1")
+        assert type.cast(:t)
+        assert type.cast(:T)
+        assert type.cast(:true)
+        assert type.cast(:TRUE)
+        assert type.cast(:on)
+        assert type.cast(:ON)
 
         # explicitly check for false vs nil
         assert_equal false, type.cast(false)
@@ -34,6 +41,13 @@ module ActiveModel
         assert_equal false, type.cast("FALSE")
         assert_equal false, type.cast("off")
         assert_equal false, type.cast("OFF")
+        assert_equal false, type.cast(:"0")
+        assert_equal false, type.cast(:f)
+        assert_equal false, type.cast(:F)
+        assert_equal false, type.cast(:false)
+        assert_equal false, type.cast(:FALSE)
+        assert_equal false, type.cast(:off)
+        assert_equal false, type.cast(:OFF)
       end
     end
   end