diff --git a/CHANGELOG.md b/CHANGELOG.md
index 34c10c4f..9110781e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Changed
 - Change no-op methods in `Shield::Hash` to `abstract def`s
 
+### Fixed
+- Limit lengths of OAuth client and bearer login names to mitigate potential DoS
+
 ## [1.2.0] - 2024-07-05
 
 ### Fixed
diff --git a/docs/14-I18N.md b/docs/14-I18N.md
index b59288b4..fb2962ec 100644
--- a/docs/14-I18N.md
+++ b/docs/14-I18N.md
@@ -200,6 +200,7 @@ en:
       name_invalid: Name is not valid
       name_not_allowed: The provided name is not allowed
       name_required: Name is required
+      name_too_long: Name cannot be longer than %{max} characters
       password_length_invalid: Password must be between %{min} and %{max} characters long
       password_notify_required: Password notification was not set
       password_required: Password is required
diff --git a/spec/shield/operations/mixins/validate_bearer_login_spec.cr b/spec/shield/operations/mixins/validate_bearer_login_spec.cr
index 3848dec9..1fa32ecf 100644
--- a/spec/shield/operations/mixins/validate_bearer_login_spec.cr
+++ b/spec/shield/operations/mixins/validate_bearer_login_spec.cr
@@ -91,6 +91,22 @@ describe Shield::ValidateBearerLogin do
     end
   end
 
+  it "rejects long name" do
+    user = UserFactory.create
+
+    SaveBearerLogin.create(params(
+      user_id: user.id,
+      active_at: Time.utc,
+      name: "t" * 300,
+      token_digest: "abc",
+      scopes: [BearerScope.new(Api::Posts::Index).to_s]
+    )) do |operation, bearer_login|
+      bearer_login.should be_nil
+
+      operation.name.should have_error("operation.error.name_too_long")
+    end
+  end
+
   it "requires a valid name format" do
     user = UserFactory.create
 
diff --git a/spec/shield/operations/mixins/validate_oauth_client_spec.cr b/spec/shield/operations/mixins/validate_oauth_client_spec.cr
index 037ca53c..dbb85360 100644
--- a/spec/shield/operations/mixins/validate_oauth_client_spec.cr
+++ b/spec/shield/operations/mixins/validate_oauth_client_spec.cr
@@ -100,6 +100,24 @@ describe Shield::ValidateOauthClient do
     end
   end
 
+  it "rejects long name" do
+    user = UserFactory.create
+
+    SaveOauthClient.create(
+      params(
+        active_at: Time.utc,
+        name: "c" * 300,
+        secret_digest: "a1b2c3",
+        user_id: user.id
+      ),
+      redirect_uris: ["https://example.com/oauth/callback"],
+    ) do |operation, oauth_client|
+      oauth_client.should be_nil
+
+      operation.name.should have_error("operation.error.name_too_long")
+    end
+  end
+
   it "requires a valid name format" do
     user = UserFactory.create
 
diff --git a/src/shield/operations/mixins/validate_bearer_login.cr b/src/shield/operations/mixins/validate_bearer_login.cr
index 54510c9f..c81d7933 100644
--- a/src/shield/operations/mixins/validate_bearer_login.cr
+++ b/src/shield/operations/mixins/validate_bearer_login.cr
@@ -5,8 +5,10 @@ module Shield::ValidateBearerLogin
     before_save do
       ensure_scopes_unique
 
-      validate_name_required
       validate_user_id_required
+
+      validate_name_required
+      validate_name_length
       validate_name_valid
       validate_name_unique
 
@@ -27,6 +29,14 @@ module Shield::ValidateBearerLogin
       validate_required name, message: Rex.t(:"operation.error.name_required")
     end
 
+    private def validate_name_length
+      max = 255
+
+      validate_size_of name,
+        max: max,
+        message: Rex.t(:"operation.error.name_too_long", max: max)
+    end
+
     private def validate_user_id_required
       validate_required user_id,
         message: Rex.t(:"operation.error.user_id_required")
diff --git a/src/shield/operations/mixins/validate_oauth_client.cr b/src/shield/operations/mixins/validate_oauth_client.cr
index 81f0bd36..6de1ec60 100644
--- a/src/shield/operations/mixins/validate_oauth_client.cr
+++ b/src/shield/operations/mixins/validate_oauth_client.cr
@@ -7,6 +7,7 @@ module Shield::ValidateOauthClient
       limit_redirect_uris_count
 
       validate_name_required
+      validate_name_length
       validate_name_unique
       validate_name_valid
       validate_name_allowed
@@ -22,8 +23,15 @@ module Shield::ValidateOauthClient
     include Lucille::ValidateUserExists
 
     private def validate_name_required
-      validate_required name,
-        message: Rex.t(:"operation.error.name_required")
+      validate_required name, message: Rex.t(:"operation.error.name_required")
+    end
+
+    private def validate_name_length
+      max = 255
+
+      validate_size_of name,
+        max: max,
+        message: Rex.t(:"operation.error.name_too_long", max: max)
     end
 
     private def validate_name_unique