diff --git a/moto/cognitoidp/exceptions.py b/moto/cognitoidp/exceptions.py
index 9bcef7fb1..b234a5238 100644
--- a/moto/cognitoidp/exceptions.py
+++ b/moto/cognitoidp/exceptions.py
@@ -43,3 +43,11 @@ class InvalidParameterException(JsonRESTError):
         super().__init__(
             "InvalidParameterException", msg or "A parameter is specified incorrectly."
         )
+
+
+class InvalidPasswordException(JsonRESTError):
+    def __init__(self) -> None:
+        super().__init__(
+            error_type="InvalidPasswordException",
+            message="The provided password does not confirm to the configured password policy",
+        )
diff --git a/moto/cognitoidp/models.py b/moto/cognitoidp/models.py
index 61ad37fdd..0b574504d 100644
--- a/moto/cognitoidp/models.py
+++ b/moto/cognitoidp/models.py
@@ -5,8 +5,6 @@ import time
 import typing
 import enum
 import re
-import boto3
-from botocore.exceptions import ClientError
 from jose import jws
 from collections import OrderedDict
 from typing import Any, Dict, List, Tuple, Optional, Set
@@ -43,10 +41,6 @@ class UserStatus(str, enum.Enum):
     UNCONFIRMED = "UNCONFIRMED"
     RESET_REQUIRED = "RESET_REQUIRED"
 
-class InvalidPasswordException(Exception):
-	"Raised when the input value is less than 18"
-	pass
-
 
 class AuthFlow(str, enum.Enum):
     # Order follows AWS' order
@@ -1612,6 +1606,10 @@ class CognitoIdpBackend(BaseBackend):
     ) -> None:
         for user_pool in self.user_pools.values():
             if access_token in user_pool.access_tokens:
+                self._validate_password(
+                    user_pool_id=user_pool.id, password=proposed_password
+                )
+
                 _, username = user_pool.access_tokens[access_token]
                 user = self.admin_get_user(user_pool.id, username)
 
@@ -1730,6 +1728,8 @@ class CognitoIdpBackend(BaseBackend):
                     "Username should be either an email or a phone number."
                 )
 
+        self._validate_password(user_pool.id, password)
+
         user = CognitoIdpUser(
             user_pool_id=user_pool.id,
             # set username to None so that it will be default to the internal GUID
@@ -1970,43 +1970,41 @@ class CognitoIdpBackend(BaseBackend):
             if sms_mfa_settings.get("PreferredMfa"):
                 user.preferred_mfa_setting = "SMS_MFA"
         return None
-		
-    def validate_password(password):            
-        tmp = password
-        lgt = len(tmp)
-        try:
-            if(lgt > 5 and lgt <99):
-                flagl = True
-            else:
-                flagl = False
-            flagn = bool(re.match("\d", tmp))
-            sc = "^ $ * . [ ] { } ( ) ? ! @ # % & / \ , > < ' : ; | _ ~ ` = + -"
-            for i in tmp:
-                if i in sc:
-                    flagsc = True
-                    break
-                else:
-                    flagsc = False
-                    
-            flagu = bool(re.match('[A-Z]+', tmp))           
-            flaglo = bool(re.match('[a-z]+', tmp))	
-            if(flagl and flagn and flagsc and flagu and flaglo):
-	        return True
-	    else:
-		raise InvalidPasswordException("The Password is invalid")
-	except ClientError as e:
-	    print(e)
-					        
+
+    def _validate_password(self, user_pool_id: str, password: str) -> None:
+        user_pool = self.describe_user_pool(user_pool_id)
+        password_policy = user_pool.extended_config.get("Policies", {}).get(
+            "PasswordPolicy", {}
+        )
+        minimum = password_policy.get("MinimumLength", 5)
+        maximum = password_policy.get("MaximumLength", 99)
+        require_uppercase = password_policy.get("RequireUppercase", True)
+        require_lowercase = password_policy.get("RequireLowercase", True)
+        require_numbers = password_policy.get("RequireNumbers", True)
+        require_symbols = password_policy.get("RequireSymbols", True)
+
+        flagl = minimum <= len(password) < maximum
+        flagn = not require_numbers or bool(re.search(r"\d", password))
+        # If we require symbols, we assume False - and check a symbol is present
+        # If we don't require symbols, we assume True - and we could technically skip the for-loop
+        flag_sc = not require_symbols
+        sc = "^ $ * . [ ] { } ( ) ? ! @ # % & / \\ , > < ' : ; | _ ~ ` = + -"
+        for i in password:
+            if i in sc:
+                flag_sc = True
+
+        flag_u = not require_uppercase or bool(re.search(r"[A-Z]+", password))
+        flag_lo = not require_lowercase or bool(re.search(r"[a-z]+", password))
+        if not (flagl and flagn and flag_sc and flag_u and flag_lo):
+            raise InvalidPasswordException()
 
     def admin_set_user_password(
         self, user_pool_id: str, username: str, password: str, permanent: bool
     ) -> None:
         user = self.admin_get_user(user_pool_id, username)
-        #user.password = password
-        flag = False
-        flag = validate_password(password)
-        if(flag == True):	
-        	user.password = password        
+        # user.password = password
+        self._validate_password(user_pool_id, password)
+        user.password = password
         if permanent:
             user.status = UserStatus.CONFIRMED
         else:
diff --git a/tests/test_cognitoidp/test_cognitoidp.py b/tests/test_cognitoidp/test_cognitoidp.py
index ea7163343..c2b5b4d85 100644
--- a/tests/test_cognitoidp/test_cognitoidp.py
+++ b/tests/test_cognitoidp/test_cognitoidp.py
@@ -1424,7 +1424,7 @@ def test_group_in_access_token():
     conn = boto3.client("cognito-idp", "us-west-2")
 
     username = str(uuid.uuid4())
-    temporary_password = str(uuid.uuid4())
+    temporary_password = "P2$Sword"
     user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
     user_attribute_name = str(uuid.uuid4())
     user_attribute_value = str(uuid.uuid4())
@@ -1460,7 +1460,7 @@ def test_group_in_access_token():
     result["Session"].should_not.equal(None)
 
     # This sets a new password and logs the user in (creates tokens)
-    new_password = str(uuid.uuid4())
+    new_password = "P2$Sword"
     result = conn.respond_to_auth_challenge(
         Session=result["Session"],
         ClientId=client_id,
@@ -2600,7 +2600,7 @@ def test_admin_delete_user_with_username_attributes():
 
 def authentication_flow(conn, auth_flow):
     username = str(uuid.uuid4())
-    temporary_password = str(uuid.uuid4())
+    temporary_password = "P2$Sword"
     user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
     user_attribute_name = str(uuid.uuid4())
     user_attribute_value = str(uuid.uuid4())
@@ -2629,7 +2629,7 @@ def authentication_flow(conn, auth_flow):
     result["Session"].should_not.equal(None)
 
     # This sets a new password and logs the user in (creates tokens)
-    new_password = str(uuid.uuid4())
+    new_password = "P2$Sword"
     result = conn.respond_to_auth_challenge(
         Session=result["Session"],
         ClientId=client_id,
@@ -2691,7 +2691,7 @@ def test_authentication_flow_invalid_user_flow():
 
 def user_authentication_flow(conn):
     username = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
     user_attribute_name = str(uuid.uuid4())
     user_attribute_value = str(uuid.uuid4())
@@ -2857,7 +2857,7 @@ def test_change_password():
         outputs = authentication_flow(conn, auth_flow)
 
         # Take this opportunity to test change_password, which requires an access token.
-        newer_password = str(uuid.uuid4())
+        newer_password = "P2$Sword2"
         conn.change_password(
             AccessToken=outputs["access_token"],
             PreviousPassword=outputs["password"],
@@ -2893,7 +2893,7 @@ def test_change_password__using_custom_user_agent_header():
         outputs = authentication_flow(conn, auth_flow)
 
         # Take this opportunity to test change_password, which requires an access token.
-        newer_password = str(uuid.uuid4())
+        newer_password = "P2$Sword2"
         conn.change_password(
             AccessToken=outputs["access_token"],
             PreviousPassword=outputs["password"],
@@ -3458,12 +3458,28 @@ def test_sign_up():
         UserPoolId=user_pool_id, ClientName=str(uuid.uuid4())
     )["UserPoolClient"]["ClientId"]
     username = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     result = conn.sign_up(ClientId=client_id, Username=username, Password=password)
     result["UserConfirmed"].should.equal(False)
     result["UserSub"].should_not.equal(None)
 
 
+@mock_cognitoidp
+@pytest.mark.parametrize("password", ["p2$$word", "P2$s"])
+def test_sign_up_with_invalid_password(password):
+    conn = boto3.client("cognito-idp", "us-west-2")
+    user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
+    client_id = conn.create_user_pool_client(
+        UserPoolId=user_pool_id, ClientName=str(uuid.uuid4())
+    )["UserPoolClient"]["ClientId"]
+    username = str(uuid.uuid4())
+
+    with pytest.raises(ClientError) as exc:
+        conn.sign_up(ClientId=client_id, Username=username, Password=password)
+    err = exc.value.response["Error"]
+    err["Code"].should.equal("InvalidPasswordException")
+
+
 @mock_cognitoidp
 def test_sign_up_with_username_attributes():
     conn = boto3.client("cognito-idp", "us-west-2")
@@ -3474,7 +3490,7 @@ def test_sign_up_with_username_attributes():
         UserPoolId=user_pool_id, ClientName=str(uuid.uuid4())
     )["UserPoolClient"]["ClientId"]
     username = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     with pytest.raises(ClientError) as err:
         # Attempt to add user again
         conn.sign_up(ClientId=client_id, Username=username, Password=password)
@@ -3500,7 +3516,7 @@ def test_sign_up_existing_user():
         UserPoolId=user_pool_id, ClientName=str(uuid.uuid4())
     )["UserPoolClient"]["ClientId"]
     username = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
 
     # Add initial user
     conn.sign_up(ClientId=client_id, Username=username, Password=password)
@@ -3516,7 +3532,7 @@ def test_sign_up_existing_user():
 def test_confirm_sign_up():
     conn = boto3.client("cognito-idp", "us-west-2")
     username = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
     client_id = conn.create_user_pool_client(
         UserPoolId=user_pool_id, ClientName=str(uuid.uuid4()), GenerateSecret=True
@@ -3535,7 +3551,7 @@ def test_confirm_sign_up():
 def test_confirm_sign_up_with_username_attributes():
     conn = boto3.client("cognito-idp", "us-west-2")
     username = "test@example.com"
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     user_pool_id = conn.create_user_pool(
         PoolName=str(uuid.uuid4()), UsernameAttributes=["email"]
     )["UserPool"]["Id"]
@@ -3556,7 +3572,7 @@ def test_confirm_sign_up_with_username_attributes():
 def test_initiate_auth_USER_SRP_AUTH():
     conn = boto3.client("cognito-idp", "us-west-2")
     username = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
     client_id = conn.create_user_pool_client(
         UserPoolId=user_pool_id, ClientName=str(uuid.uuid4()), GenerateSecret=True
@@ -3592,7 +3608,7 @@ def test_initiate_auth_USER_SRP_AUTH():
 def test_initiate_auth_USER_SRP_AUTH_with_username_attributes():
     conn = boto3.client("cognito-idp", "us-west-2")
     username = "test@example.com"
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     user_pool_id = conn.create_user_pool(
         PoolName=str(uuid.uuid4()), UsernameAttributes=["email"]
     )["UserPool"]["Id"]
@@ -3726,7 +3742,7 @@ def test_initiate_auth_USER_PASSWORD_AUTH_with_FORCE_CHANGE_PASSWORD_status():
     )["UserPoolClient"]["ClientId"]
 
     # Create user in status FORCE_CHANGE_PASSWORD
-    temporary_password = str(uuid.uuid4())
+    temporary_password = "P2$Sword"
     client.admin_create_user(
         UserPoolId=user_pool_id, Username=username, TemporaryPassword=temporary_password
     )
@@ -3742,7 +3758,7 @@ def test_initiate_auth_USER_PASSWORD_AUTH_with_FORCE_CHANGE_PASSWORD_status():
     result["Session"].should_not.equal("")
     assert result.get("AuthenticationResult") is None
 
-    new_password = str(uuid.uuid4())
+    new_password = "P2$Sword2"
     result = client.respond_to_auth_challenge(
         ClientId=client_id,
         ChallengeName="NEW_PASSWORD_REQUIRED",
@@ -3792,7 +3808,7 @@ def test_initiate_auth_USER_PASSWORD_AUTH_user_incorrect_password():
 def test_initiate_auth_USER_PASSWORD_AUTH_unconfirmed_user():
     conn = boto3.client("cognito-idp", "us-west-2")
     username = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
     client_id = conn.create_user_pool_client(
         UserPoolId=user_pool_id, ClientName=str(uuid.uuid4()), GenerateSecret=True
@@ -3813,7 +3829,7 @@ def test_initiate_auth_USER_PASSWORD_AUTH_unconfirmed_user():
 def test_initiate_auth_for_unconfirmed_user():
     conn = boto3.client("cognito-idp", "us-west-2")
     username = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
     client_id = conn.create_user_pool_client(
         UserPoolId=user_pool_id, ClientName=str(uuid.uuid4()), GenerateSecret=True
@@ -3846,7 +3862,7 @@ def test_initiate_auth_for_unconfirmed_user():
 def test_initiate_auth_with_invalid_secret_hash():
     conn = boto3.client("cognito-idp", "us-west-2")
     username = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$Sword"
     user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
     client_id = conn.create_user_pool_client(
         UserPoolId=user_pool_id, ClientName=str(uuid.uuid4()), GenerateSecret=True
@@ -4000,7 +4016,7 @@ def test_admin_set_user_password():
 
     username = str(uuid.uuid4())
     value = str(uuid.uuid4())
-    password = str(uuid.uuid4())
+    password = "P2$$word"
     user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
     conn.admin_create_user(
         UserPoolId=user_pool_id,
@@ -4022,6 +4038,73 @@ def test_admin_set_user_password():
     _verify_attribute("thing", value)
 
 
+@mock_cognitoidp
+@pytest.mark.parametrize("password", ["pa$$word", "Password", "p2ssword", "P2$S"])
+def test_admin_set_invalid_user_password(password):
+    conn = boto3.client("cognito-idp", "us-west-2")
+
+    username = str(uuid.uuid4())
+    value = str(uuid.uuid4())
+    user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
+    conn.admin_create_user(
+        UserPoolId=user_pool_id,
+        Username=username,
+        UserAttributes=[{"Name": "thing", "Value": value}],
+    )
+    with pytest.raises(ClientError) as exc:
+        conn.admin_set_user_password(
+            UserPoolId=user_pool_id,
+            Username=username,
+            Password=password,
+            Permanent=True,
+        )
+    err = exc.value.response["Error"]
+    err["Code"].should.equal("InvalidPasswordException")
+
+
+@mock_cognitoidp
+@pytest.mark.parametrize("password", ["password", "P2$$word"])
+def test_admin_set_invalid_user_password__custom_policy_provided(password):
+    conn = boto3.client("cognito-idp", "us-west-2")
+
+    username = str(uuid.uuid4())
+    value = str(uuid.uuid4())
+    user_pool_id = conn.create_user_pool(
+        PoolName=str(uuid.uuid4()),
+        Policies={
+            "PasswordPolicy": {
+                "MinimumLength": 12,
+                "RequireUppercase": False,
+                "RequireLowercase": False,
+                "RequireNumbers": False,
+                "RequireSymbols": False,
+            }
+        },
+    )["UserPool"]["Id"]
+    conn.admin_create_user(
+        UserPoolId=user_pool_id,
+        Username=username,
+        UserAttributes=[{"Name": "thing", "Value": value}],
+    )
+    with pytest.raises(ClientError) as exc:
+        conn.admin_set_user_password(
+            UserPoolId=user_pool_id,
+            Username=username,
+            Password=password,
+            Permanent=True,
+        )
+    err = exc.value.response["Error"]
+    err["Code"].should.equal("InvalidPasswordException")
+
+    # We can set a plain password, as long as it's 12 characters long
+    conn.admin_set_user_password(
+        UserPoolId=user_pool_id,
+        Username=username,
+        Password="longpassword",
+        Permanent=True,
+    )
+
+
 @mock_cognitoidp
 def test_change_password_with_invalid_token_raises_error():
     client = boto3.client("cognito-idp", "us-west-2")
diff --git a/tests/test_cognitoidp/test_cognitoidp_exceptions.py b/tests/test_cognitoidp/test_cognitoidp_exceptions.py
index f9452ee35..ec19de0a0 100644
--- a/tests/test_cognitoidp/test_cognitoidp_exceptions.py
+++ b/tests/test_cognitoidp/test_cognitoidp_exceptions.py
@@ -18,18 +18,21 @@ class TestCognitoUserDeleter(TestCase):
 
     def test_authenticate_with_signed_out_user(self):
         self.client.admin_create_user(
-            UserPoolId=self.pool_id, Username="foo", TemporaryPassword="bar"
+            UserPoolId=self.pool_id, Username="foo", TemporaryPassword="P2$Sword"
         )
 
         self.client.admin_set_user_password(
-            UserPoolId=self.pool_id, Username="foo", Password="bar", Permanent=True
+            UserPoolId=self.pool_id,
+            Username="foo",
+            Password="P2$Sword2",
+            Permanent=True,
         )
 
         response = self.client.admin_initiate_auth(
             UserPoolId=self.pool_id,
             ClientId=self.client_id,
             AuthFlow="ADMIN_USER_PASSWORD_AUTH",
-            AuthParameters={"USERNAME": "foo", "PASSWORD": "bar"},
+            AuthParameters={"USERNAME": "foo", "PASSWORD": "P2$Sword2"},
         )
 
         refresh_token = response["AuthenticationResult"]["RefreshToken"]
diff --git a/tests/test_cognitoidp/test_server.py b/tests/test_cognitoidp/test_server.py
index 8098f332b..c14b42316 100644
--- a/tests/test_cognitoidp/test_server.py
+++ b/tests/test_cognitoidp/test_server.py
@@ -47,7 +47,7 @@ def test_sign_up_user_without_authentication():
     json.loads(res.data)["UserPoolClients"].should.have.length_of(1)
 
     # Sign Up User
-    data = {"ClientId": client_id, "Username": "test@gmail.com", "Password": "12345678"}
+    data = {"ClientId": client_id, "Username": "test@gmail.com", "Password": "P2$Sword"}
     res = test_client.post(
         "/",
         data=json.dumps(data),
@@ -72,7 +72,7 @@ def test_sign_up_user_without_authentication():
     data = {
         "ClientId": client_id,
         "AuthFlow": "USER_PASSWORD_AUTH",
-        "AuthParameters": {"USERNAME": "test@gmail.com", "PASSWORD": "12345678"},
+        "AuthParameters": {"USERNAME": "test@gmail.com", "PASSWORD": "P2$Sword"},
     }
     res = test_client.post(
         "/",