diff --git a/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidator.kt b/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidator.kt
index dda3a4d6dc..0579e215b6 100644
--- a/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidator.kt
+++ b/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidator.kt
@@ -97,6 +97,10 @@ object EnvelopeContentValidator {
       return Result.Invalid("[DataMessage] Invalid ACI on quote body range!")
     }
 
+    if (dataMessage.quote != null && dataMessage.quote.bodyRanges.any { it.isStyleRangeMissingOffsets() }) {
+      return Result.Invalid("[DataMessage] Style body range on quote is missing a start or length!")
+    }
+
     if (dataMessage.quote != null && dataMessage.quote.bodyRanges.hasInvalidBounds(dataMessage.quote.text)) {
       return Result.Invalid("[DataMessage] Quote body range with out-of-bounds start/length!")
     }
@@ -113,6 +117,10 @@ object EnvelopeContentValidator {
       return Result.Invalid("[DataMessage] Invalid ACI on body range!")
     }
 
+    if (dataMessage.bodyRanges.any { it.isStyleRangeMissingOffsets() }) {
+      return Result.Invalid("[DataMessage] Style body range is missing a start or length!")
+    }
+
     if (dataMessage.bodyRanges.hasInvalidBounds(dataMessage.body)) {
       return Result.Invalid("[DataMessage] Body range with out-of-bounds start/length!")
     }
@@ -363,6 +371,10 @@ object EnvelopeContentValidator {
       return Result.Invalid("[EditMessage] Invalid UUID on body range!")
     }
 
+    if (dataMessage.bodyRanges.any { it.isStyleRangeMissingOffsets() }) {
+      return Result.Invalid("[EditMessage] Style body range is missing a start or length!")
+    }
+
     if (dataMessage.bodyRanges.hasInvalidBounds(dataMessage.body)) {
       return Result.Invalid("[EditMessage] Body range with out-of-bounds start/length!")
     }
@@ -389,6 +401,10 @@ object EnvelopeContentValidator {
     }
   }
 
+  private fun BodyRange.isStyleRangeMissingOffsets(): Boolean {
+    return this.style != null && (this.start == null || this.length == null)
+  }
+
   private fun AttachmentPointer?.isNullOrInvalid(): Boolean {
     return this == null || (this.cdnId == null && this.cdnKey == null)
   }
diff --git a/lib/libsignal-service/src/test/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidatorTest.kt b/lib/libsignal-service/src/test/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidatorTest.kt
index 8560f37545..748391dfe9 100644
--- a/lib/libsignal-service/src/test/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidatorTest.kt
+++ b/lib/libsignal-service/src/test/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidatorTest.kt
@@ -428,6 +428,71 @@ class EnvelopeContentValidatorTest {
     assert(result is EnvelopeContentValidator.Result.Valid)
   }
 
+  @Test
+  fun `validate - ensure style body range missing start is marked invalid`() {
+    val content = Content(
+      dataMessage = DataMessage(
+        timestamp = 1234,
+        bodyRanges = listOf(
+          BodyRange(length = 1, style = BodyRange.Style.BOLD)
+        )
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(clientTimestamp = 1234), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Invalid)
+  }
+
+  @Test
+  fun `validate - ensure style body range missing length is marked invalid`() {
+    val content = Content(
+      dataMessage = DataMessage(
+        timestamp = 1234,
+        bodyRanges = listOf(
+          BodyRange(start = 0, style = BodyRange.Style.BOLD)
+        )
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(clientTimestamp = 1234), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Invalid)
+  }
+
+  @Test
+  fun `validate - ensure style body range with both start and length is marked valid`() {
+    val content = Content(
+      dataMessage = DataMessage(
+        timestamp = 1234,
+        body = "hello",
+        bodyRanges = listOf(
+          BodyRange(start = 0, length = 1, style = BodyRange.Style.BOLD)
+        )
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(clientTimestamp = 1234), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Valid)
+  }
+
+  @Test
+  fun `validate - ensure quote style body range missing start is marked invalid`() {
+    val content = Content(
+      dataMessage = DataMessage(
+        timestamp = 1234,
+        quote = DataMessage.Quote(
+          id = 1000,
+          authorAci = OTHER_ACI.toString(),
+          bodyRanges = listOf(
+            BodyRange(length = 1, style = BodyRange.Style.BOLD)
+          )
+        )
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(clientTimestamp = 1234), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Invalid)
+  }
+
   @Test
   fun `validate - ensure sync blocked with invalid string aci and empty binary list is marked invalid`() {
     val envelope = Envelope(sourceServiceId = SELF_ACI.toString())