diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index 1748539bef..82a9e41dbd 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -7,6 +7,9 @@
     *   Add source prefix to all `Format.id` fields generated from
         `MergingMediaSource`. This helps to identify which source produced a
         `Format` ([#883](https://github.com/androidx/media/issues/883)).
+    *   Fix the regex used for validating custom Common Media Client Data (CMCD)
+        key names by modifying it to only check for hyphen
+        ([#1028](https://github.com/androidx/media/issues/1028)).
 *   Transformer:
 *   Track Selection:
 *   Extractors:
diff --git a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/upstream/CmcdData.java b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/upstream/CmcdData.java
index d84c592522..1ebd6727f9 100644
--- a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/upstream/CmcdData.java
+++ b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/upstream/CmcdData.java
@@ -89,8 +89,12 @@ public final class CmcdData {
     /** Represents the object type for muxed audio and video content in a media container. */
     public static final String OBJECT_TYPE_MUXED_AUDIO_AND_VIDEO = "av";
 
-    private static final Pattern CUSTOM_KEY_NAME_PATTERN =
-        Pattern.compile("[a-zA-Z0-9]+(-[a-zA-Z0-9]+)+");
+    /**
+     * Custom key names MUST carry a hyphenated prefix to ensure that there will not be a namespace
+     * collision with future revisions to this specification. Clients SHOULD use a reverse-DNS
+     * syntax when defining their own prefix.
+     */
+    private static final Pattern CUSTOM_KEY_NAME_PATTERN = Pattern.compile(".*-.*");
 
     private final CmcdConfiguration cmcdConfiguration;
     private final ExoTrackSelection trackSelection;
diff --git a/libraries/exoplayer_dash/src/test/java/androidx/media3/exoplayer/dash/DefaultDashChunkSourceTest.java b/libraries/exoplayer_dash/src/test/java/androidx/media3/exoplayer/dash/DefaultDashChunkSourceTest.java
index 7de944c718..37d89a3e78 100644
--- a/libraries/exoplayer_dash/src/test/java/androidx/media3/exoplayer/dash/DefaultDashChunkSourceTest.java
+++ b/libraries/exoplayer_dash/src/test/java/androidx/media3/exoplayer/dash/DefaultDashChunkSourceTest.java
@@ -459,8 +459,8 @@ public class DefaultDashChunkSourceTest {
                           @CmcdConfiguration.HeaderKey String, String>()
                       .put(CmcdConfiguration.KEY_CMCD_OBJECT, "key-1=1")
                       .put(CmcdConfiguration.KEY_CMCD_REQUEST, "key-2=\"stringValue\"")
-                      .put(CmcdConfiguration.KEY_CMCD_SESSION, "key-3=3")
-                      .put(CmcdConfiguration.KEY_CMCD_STATUS, "key-4=5.0")
+                      .put(CmcdConfiguration.KEY_CMCD_SESSION, "com.example-key3=3")
+                      .put(CmcdConfiguration.KEY_CMCD_STATUS, "com.example.test-key4=5.0")
                       .build();
                 }
               };
@@ -487,9 +487,11 @@ public class DefaultDashChunkSourceTest {
             "CMCD-Request",
             "bl=0,dl=0,key-2=\"stringValue\",mtp=1000,nor=\"..%2Fvideo_4000_700000.m4s\",nrr=\"0-\",su",
             "CMCD-Session",
-            "cid=\"mediaId\",key-3=3,sf=d,sid=\"" + cmcdConfiguration.sessionId + "\",st=v",
+            "cid=\"mediaId\",com.example-key3=3,sf=d,sid=\""
+                + cmcdConfiguration.sessionId
+                + "\",st=v",
             "CMCD-Status",
-            "key-4=5.0");
+            "com.example.test-key4=5.0");
   }
 
   @Test
@@ -505,7 +507,7 @@ public class DefaultDashChunkSourceTest {
                     getCustomData() {
                   return new ImmutableListMultimap.Builder<
                           @CmcdConfiguration.HeaderKey String, String>()
-                      .put(CmcdConfiguration.KEY_CMCD_OBJECT, "key-1=1")
+                      .put(CmcdConfiguration.KEY_CMCD_OBJECT, "com.example.test-key-1=1")
                       .put(CmcdConfiguration.KEY_CMCD_REQUEST, "key-2=\"stringValue\"")
                       .build();
                 }
@@ -534,9 +536,9 @@ public class DefaultDashChunkSourceTest {
                 output.chunk.dataSpec.uri.getQueryParameter(
                     CmcdConfiguration.CMCD_QUERY_PARAMETER_KEY)))
         .isEqualTo(
-            "bl=0,br=700,cid=\"mediaId\",d=4000,dl=0,key-1=1,key-2=\"stringValue\","
-                + "mtp=1000,nor=\"..%2Fvideo_4000_700000.m4s\",nrr=\"0-\",ot=v,sf=d,"
-                + "sid=\"sessionId\",st=v,su,tb=1300");
+            "bl=0,br=700,cid=\"mediaId\",com.example.test-key-1=1,d=4000,dl=0,"
+                + "key-2=\"stringValue\",mtp=1000,nor=\"..%2Fvideo_4000_700000.m4s\",nrr=\"0-\","
+                + "ot=v,sf=d,sid=\"sessionId\",st=v,su,tb=1300");
   }
 
   @Test
diff --git a/libraries/exoplayer_hls/src/test/java/androidx/media3/exoplayer/hls/HlsChunkSourceTest.java b/libraries/exoplayer_hls/src/test/java/androidx/media3/exoplayer/hls/HlsChunkSourceTest.java
index a038217103..303e4c1bb6 100644
--- a/libraries/exoplayer_hls/src/test/java/androidx/media3/exoplayer/hls/HlsChunkSourceTest.java
+++ b/libraries/exoplayer_hls/src/test/java/androidx/media3/exoplayer/hls/HlsChunkSourceTest.java
@@ -367,8 +367,8 @@ public class HlsChunkSourceTest {
                           @CmcdConfiguration.HeaderKey String, String>()
                       .put(CmcdConfiguration.KEY_CMCD_OBJECT, "key-1=1")
                       .put(CmcdConfiguration.KEY_CMCD_REQUEST, "key-2=\"stringValue\"")
-                      .put(CmcdConfiguration.KEY_CMCD_SESSION, "key-3=3")
-                      .put(CmcdConfiguration.KEY_CMCD_STATUS, "key-4=5.0")
+                      .put(CmcdConfiguration.KEY_CMCD_SESSION, "com.example-key3=3")
+                      .put(CmcdConfiguration.KEY_CMCD_STATUS, "com.example.test-key4=5.0")
                       .build();
                 }
               };
@@ -396,9 +396,11 @@ public class HlsChunkSourceTest {
             "CMCD-Request",
             "bl=0,dl=0,key-2=\"stringValue\",nor=\"..%2F3.mp4\",nrr=\"0-\",su",
             "CMCD-Session",
-            "cid=\"mediaId\",key-3=3,sf=h,sid=\"" + cmcdConfiguration.sessionId + "\",st=v",
+            "cid=\"mediaId\",com.example-key3=3,sf=h,sid=\""
+                + cmcdConfiguration.sessionId
+                + "\",st=v",
             "CMCD-Status",
-            "key-4=5.0");
+            "com.example.test-key4=5.0");
   }
 
   @Test
@@ -414,7 +416,7 @@ public class HlsChunkSourceTest {
                     getCustomData() {
                   return new ImmutableListMultimap.Builder<
                           @CmcdConfiguration.HeaderKey String, String>()
-                      .put(CmcdConfiguration.KEY_CMCD_OBJECT, "key-1=1")
+                      .put(CmcdConfiguration.KEY_CMCD_OBJECT, "com.example.test-key-1=1")
                       .put(CmcdConfiguration.KEY_CMCD_REQUEST, "key-2=\"stringValue\"")
                       .build();
                 }
@@ -444,8 +446,9 @@ public class HlsChunkSourceTest {
                 output.chunk.dataSpec.uri.getQueryParameter(
                     CmcdConfiguration.CMCD_QUERY_PARAMETER_KEY)))
         .isEqualTo(
-            "bl=0,br=800,cid=\"mediaId\",d=4000,dl=0,key-1=1,key-2=\"stringValue\","
-                + "nor=\"..%2F3.mp4\",nrr=\"0-\",ot=v,sf=h,sid=\"sessionId\",st=v,su,tb=800");
+            "bl=0,br=800,cid=\"mediaId\",com.example.test-key-1=1,d=4000,dl=0,"
+                + "key-2=\"stringValue\",nor=\"..%2F3.mp4\",nrr=\"0-\",ot=v,sf=h,"
+                + "sid=\"sessionId\",st=v,su,tb=800");
   }
 
   private HlsChunkSource createHlsChunkSource(@Nullable CmcdConfiguration cmcdConfiguration) {
diff --git a/libraries/exoplayer_smoothstreaming/src/test/java/androidx/media3/exoplayer/smoothstreaming/DefaultSsChunkSourceTest.java b/libraries/exoplayer_smoothstreaming/src/test/java/androidx/media3/exoplayer/smoothstreaming/DefaultSsChunkSourceTest.java
index d04906cf70..89a7307ba0 100644
--- a/libraries/exoplayer_smoothstreaming/src/test/java/androidx/media3/exoplayer/smoothstreaming/DefaultSsChunkSourceTest.java
+++ b/libraries/exoplayer_smoothstreaming/src/test/java/androidx/media3/exoplayer/smoothstreaming/DefaultSsChunkSourceTest.java
@@ -210,8 +210,8 @@ public class DefaultSsChunkSourceTest {
                           @CmcdConfiguration.HeaderKey String, String>()
                       .put(CmcdConfiguration.KEY_CMCD_OBJECT, "key-1=1")
                       .put(CmcdConfiguration.KEY_CMCD_REQUEST, "key-2=\"stringValue\"")
-                      .put(CmcdConfiguration.KEY_CMCD_SESSION, "key-3=3")
-                      .put(CmcdConfiguration.KEY_CMCD_STATUS, "key-4=5.0")
+                      .put(CmcdConfiguration.KEY_CMCD_SESSION, "com.example-key3=3")
+                      .put(CmcdConfiguration.KEY_CMCD_STATUS, "com.example.test-key4=5.0")
                       .build();
                 }
               };
@@ -238,9 +238,11 @@ public class DefaultSsChunkSourceTest {
             "CMCD-Request",
             "bl=0,dl=0,key-2=\"stringValue\",mtp=1000,nor=\"..%2FFragments(video%3D19680000)\",su",
             "CMCD-Session",
-            "cid=\"mediaId\",key-3=3,sf=s,sid=\"" + cmcdConfiguration.sessionId + "\",st=v",
+            "cid=\"mediaId\",com.example-key3=3,sf=s,sid=\""
+                + cmcdConfiguration.sessionId
+                + "\",st=v",
             "CMCD-Status",
-            "key-4=5.0");
+            "com.example.test-key4=5.0");
   }
 
   @Test
@@ -256,7 +258,7 @@ public class DefaultSsChunkSourceTest {
                     getCustomData() {
                   return new ImmutableListMultimap.Builder<
                           @CmcdConfiguration.HeaderKey String, String>()
-                      .put(CmcdConfiguration.KEY_CMCD_OBJECT, "key-1=1")
+                      .put(CmcdConfiguration.KEY_CMCD_OBJECT, "com.example.test-key-1=1")
                       .put(CmcdConfiguration.KEY_CMCD_REQUEST, "key-2=\"stringValue\"")
                       .build();
                 }
@@ -285,9 +287,9 @@ public class DefaultSsChunkSourceTest {
                 output.chunk.dataSpec.uri.getQueryParameter(
                     CmcdConfiguration.CMCD_QUERY_PARAMETER_KEY)))
         .isEqualTo(
-            "bl=0,br=308,cid=\"mediaId\",d=1968,dl=0,key-1=1,key-2=\"stringValue\","
-                + "mtp=1000,nor=\"..%2FFragments(video%3D19680000)\",ot=v,sf=s,sid=\"sessionId\","
-                + "st=v,su,tb=1536");
+            "bl=0,br=308,cid=\"mediaId\",com.example.test-key-1=1,d=1968,dl=0,"
+                + "key-2=\"stringValue\",mtp=1000,nor=\"..%2FFragments(video%3D19680000)\",ot=v,"
+                + "sf=s,sid=\"sessionId\",st=v,su,tb=1536");
   }
 
   private SsChunkSource createSsChunkSource(