diff --git a/subprojects/dependency-management/src/integTest/groovy/org/gradle/integtests/resolve/attributes/DependenciesAttributesIntegrationTest.groovy b/subprojects/dependency-management/src/integTest/groovy/org/gradle/integtests/resolve/attributes/DependenciesAttributesIntegrationTest.groovy
index ddbf42fc9d2f..9d936c340058 100644
--- a/subprojects/dependency-management/src/integTest/groovy/org/gradle/integtests/resolve/attributes/DependenciesAttributesIntegrationTest.groovy
+++ b/subprojects/dependency-management/src/integTest/groovy/org/gradle/integtests/resolve/attributes/DependenciesAttributesIntegrationTest.groovy
@@ -506,6 +506,65 @@ class DependenciesAttributesIntegrationTest extends AbstractModuleDependencyReso
         'c1'               | 'c2'            | 'runtime'       | ['org.gradle.status': defaultStatus(), 'org.gradle.usage': 'java-runtime', 'org.gradle.libraryelements': 'jar', 'org.gradle.category': 'library', custom: 'c2']
     }
 
+    @Issue("https://github.com/gradle/gradle/issues/20182")
+    @RequiredFeature(feature = GradleMetadataResolveRunner.GRADLE_METADATA, value = "true")
+    @Unroll("Selects variant #expectedVariant using custom attribute value #dependencyValue overriding configuration attribute #configurationValue using dependency constraint without version")
+    def "dependency attribute value overrides configuration attribute using dependency constraint without version"() {
+        given:
+        repository {
+            'org:test:1.0' {
+                variant('api') {
+                    attribute('custom', 'c1')
+                }
+                variant('runtime') {
+                    attribute('custom', 'c2')
+                }
+            }
+        }
+
+        buildFile << """
+            configurations.conf.attributes.attribute(CUSTOM_ATTRIBUTE, '$configurationValue')
+
+            dependencies {
+                constraints {
+                    conf('org:test') {
+                       attributes {
+                          attribute(CUSTOM_ATTRIBUTE, '$dependencyValue')
+                       }
+                    }
+                }
+                conf 'org:test:1.0'
+            }
+        """
+
+        when:
+        repositoryInteractions {
+            'org:test:1.0' {
+                expectResolve()
+            }
+        }
+        succeeds 'checkDeps'
+
+        then:
+        resolve.expectGraph {
+            root(":", ":test:") {
+                module('org:test:1.0') {
+                    configuration = expectedVariant
+                    variant(expectedVariant, expectedAttributes)
+                }
+                constraint('org:test', 'org:test:1.0') {
+                    configuration = expectedVariant
+                    variant(expectedVariant, expectedAttributes)
+                }
+            }
+        }
+
+        where:
+        configurationValue | dependencyValue | expectedVariant | expectedAttributes
+        'c2'               | 'c1'            | 'api'           | ['org.gradle.status': defaultStatus(), 'org.gradle.usage': 'java-api', 'org.gradle.libraryelements': 'jar', 'org.gradle.category': 'library', custom: 'c1']
+        'c1'               | 'c2'            | 'runtime'       | ['org.gradle.status': defaultStatus(), 'org.gradle.usage': 'java-runtime', 'org.gradle.libraryelements': 'jar', 'org.gradle.category': 'library', custom: 'c2']
+    }
+
     @RequiredFeature(feature = GradleMetadataResolveRunner.GRADLE_METADATA, value = "true")
     @ToBeFixedForConfigurationCache
     def "Fails resolution because consumer configuration attributes and constraint attributes conflict"() {
diff --git a/subprojects/dependency-management/src/main/java/org/gradle/api/internal/artifacts/ivyservice/ivyresolve/parser/GradleModuleMetadataParser.java b/subprojects/dependency-management/src/main/java/org/gradle/api/internal/artifacts/ivyservice/ivyresolve/parser/GradleModuleMetadataParser.java
index 030c47aee756..5edc958813da 100644
--- a/subprojects/dependency-management/src/main/java/org/gradle/api/internal/artifacts/ivyservice/ivyresolve/parser/GradleModuleMetadataParser.java
+++ b/subprojects/dependency-management/src/main/java/org/gradle/api/internal/artifacts/ivyservice/ivyresolve/parser/GradleModuleMetadataParser.java
@@ -439,7 +439,7 @@ private List<ModuleDependencyConstraint> consumeDependencyConstraints(JsonReader
             String group = null;
             String module = null;
             String reason = null;
-            VersionConstraint version = null;
+            VersionConstraint version = DefaultImmutableVersionConstraint.of();
             ImmutableAttributes attributes = ImmutableAttributes.EMPTY;
 
             reader.beginObject();
diff --git a/subprojects/dependency-management/src/test/groovy/org/gradle/api/internal/artifacts/ivyservice/ivyresolve/parser/GradleModuleMetadataParserTest.groovy b/subprojects/dependency-management/src/test/groovy/org/gradle/api/internal/artifacts/ivyservice/ivyresolve/parser/GradleModuleMetadataParserTest.groovy
index 88abade1f193..feaa387f61fe 100644
--- a/subprojects/dependency-management/src/test/groovy/org/gradle/api/internal/artifacts/ivyservice/ivyresolve/parser/GradleModuleMetadataParserTest.groovy
+++ b/subprojects/dependency-management/src/test/groovy/org/gradle/api/internal/artifacts/ivyservice/ivyresolve/parser/GradleModuleMetadataParserTest.groovy
@@ -381,7 +381,8 @@ class GradleModuleMetadataParserTest extends Specification {
                         "group": "g3",
                         "module": "m3",
                         "version": { "requires": "v3" }
-                    }
+                    },
+                    { "group": "g4", "module": "m4" }
                 ],
                 "attributes": { "usage": "compile" }
             },
@@ -404,6 +405,7 @@ class GradleModuleMetadataParserTest extends Specification {
         1 * variant1.addDependencyConstraint("g1", "m1", requires("v1"), null, ImmutableAttributes.EMPTY)
         1 * variant1.addDependencyConstraint("g2", "m2", prefers("v2"), null, ImmutableAttributes.EMPTY)
         1 * variant1.addDependencyConstraint("g3", "m3", requires("v3"), null, ImmutableAttributes.EMPTY)
+        1 * variant1.addDependencyConstraint("g4", "m4", emptyConstraint(), null, ImmutableAttributes.EMPTY)
         1 * variant1.setAvailableExternally(false)
         1 * metadata.addVariant("runtime", attributes(usage: "runtime", packaging: "zip")) >> variant2
         1 * variant2.addDependencyConstraint("g3", "m3", prefers("v3"), null, ImmutableAttributes.EMPTY)