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Checks CloudFormation templates for practices and behaviour that could potentially be improved
Last release today
29 Sep 2026
Ships on a steady schedule
a new release about every 9 days
Nearly every release is documented
notes for 59 of the last 60 stable releases
Nothing withdrawn
no release was ever pulled
8 years old
458 releases · first in 2018
Update rule E3026 to better check for condition scenarios and not fail (pull #1327)
Update CloudFormation patches to include pricing and SSM data from 2020.01.20 (pull #1322)
One column per quarter.
Add additional configuration checks to rule E2001 (pull #1301)
Export Name required from Outputs in rule E6002 to E6001 (pull #1301)Outputs Value in rule E6003 to E6001 (pull #1301)Add extra attributes to rules E1024, E3027, E3020 (pull #1272)
AWS::S3::Bucket.RoutingRuleCondition properties from OnlyOne to AtLeastOne (pull #1283)AWS::SSM::Parameter.Value to the AWS::EC2::VPC.Id type (pull #1288)CNAME as an allowed value to ServiceDiscoveryDnsType (pull #1296)AWS::WAFv2::RegexPatternSet.RegularExpressionList removing extra layer (pull #1300)LambdaProvisionedConcurrencyUtilization as allowed value to Application Autoscaling Metric (pull #1303)AWS::CloudWatch::Alarm for Metrics and Threshold (pull #1306)Update aws-sam-translator to 1.19.1 (pull #1275)
New rule I3011 to check stateful resources have a set UpdateReplacePolicy/DeletionPolicy (pull #1232)
Created a new mandatory-checks parameter to require rules to be reported on and not ignored (pull #1243)
mandatory-checks parameter to require rules to be reported on and not ignored (pull #1243)append-rules (pull #1216)us-west-2-lax-1a (pull #1241)Update pricing and services from 2019.12.02 (pull #1237)
Update CloudFormation specs to 9.1.0 (pull #1224)
Change DocDB allowed EngineVersion value to 3.6.0 (pull #1213)
Add capacityOptimized to spot fleet allocation strategy (pull #1200)
Update allowed values for AWS Config types (pull #1197)
Add rule I1022 to recommend Sub over Join when join is using empty delimiter (pull #1067)
Update CloudFormation specs to 7.2.0 (pull #1177)
Patch in Tags for SNS Topics (pull #1174)
Update SAM Translator to 1.15.1 (pull #1166)
Update CloudFormation specs to 7.1.0 (pull #1163)
Update CloudFormation specs to 6.3.0 (pull #1155)
Add link to updated IntelliJ integration (pull #1138)
Add missing values for LifecyclePolicy API (pull #1128)
Update CloudFormation specs to 6.0.0 (pull #1126)
Move rule classes from cfnlint into cfnlint.rules (pull #1098)
Switch AWS Batch SpotIamFleetRole to Role Arn (pull #1111)
Update CloudFormatin specs to 5.3.0 (pull #1108)
Add me-east-1 CloudFormation spec (pull #1095)
Update CloudFormation spec to version 5.0.0 (pull #1087)
Fix an issue where anything piped into cfn-lint would result in ignoring the templates parameter (pull #1081)
Add support for regions cn-north-1 and cn-northwest-1 (pull #1051)
Add ALL_REGIONS option for -r flag (pull #1026)
Patch in AWS::SageMaker::CodeRepository to the CloudFormation spec (issue #1005)
AWS::SageMaker::CodeRepository to the CloudFormation spec (issue #1005)Patch in AWS::Cognito::UserPool resource information for ap-south-1 and ap-southeast-1 (issue #1002)
AWS::Cognito::UserPool resource information for ap-south-1 and ap-southeast-1 (issue #1002)AWS::Backup::BackupPlan resource information and fix a few spec issues (pull #1006)- inside [] (issue #997)\ in the prefix (issue #1009)Add INSTANCE to DLMPolicyResourceType allowed values (pull #995)
INSTANCE to DLMPolicyResourceType allowed values (pull #995)Added LaunchTemplateId/LaunchTemplateName of the AutoScalingGroup to the OnlyOne
Remove rule W2507 and use rule E3008 instead
Update rule E3001 to validate that a Resource Condition is a string
Include more resource types in W3037
AWS::CDK::MetadataSupport dumping strings for datetime objects when doing a Transform
Update CloudFormation specs to 3.3.0
Add Info logging capability and set the default logging to NotSet
Info logging capability and set the default logging to NotSetFn::Transform inside a Fn::SubFn::Transform inside a Fn::Subnetwork load balancer when an object is used for the Load Balancer typeNew rule E2531 to validate a Lambda's runtime against the deprecated dates
Update instance types from pricing API as of 2019.05.16
Add support for List Parameter types
Update rule E8003 to support more functions inside a Fn::Equals
Allow a rule's exception to be defined in a resource's metadata
Fix core Condition processing to support direct Condition in another Condition
Add NS and PTR Route53 record checking to rule E3020
Update CloudFormation Specs to 2.30.0
New rule E3032 to check the size of lists
ListMin and ListMax for the minimum and maximum size of a listJsonMax to check the max size of a JSON ObjectStringMin and StringMax to check the minimum and maximum length of a StringNumberMin and NumberMax to check the minimum and maximum value of a Number, Float, LongUpdate rule E2503 to make sure NLBs don't have a Security Group configured
AWS::Glue ResourcesAWS::CloudWatch::Alarm to only MetricName or MetricsAWS::CloudWatch::Alarm for properties mixed with Metrics and Statistic[0-9A-Za-z_-]+Parameters inside a Pass actionAdd new rule E3026 to validate Redis cluster settings including AutomaticFailoverEnabled and NumCacheClusters. Status: Released
-e/--include-experimental to allow for new rules in that aren't ready to be fully releasedAdd rule E3031 to look for regex patterns based on the patched spec file
ignore-templates to allow the ignoring of templates when doing bulk lintingawslabs to aws-cloudformation organizationAdd scaffolding for arbitrary Match attributes, adding attributes for Type checks
Update CloudFormation Specs to version 2.23.0
Add rule E3035 to check the values of DeletionPolicy
Fix CloudWatchAlarmComparisonOperator allowed values.
Add allowed values for AWS::CloudTrail::Trail resources
New rule W1011 to check if a FindInMap is using the correct map name and keys
--template wouldn't be used when a .cfnlintrc was in the same folderAdd AWS::WorkSpaces::Workspace.WorkspaceProperties ComputeTypeName, RunningMode allowed values
Update rule E1019 to not allow for lists directly when doing a Ref or GetAtt to a list
Support Ref to IAM::Role or IAM::InstanceProfile with values looking for an ARN
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