From ec2a8d37d6429d97ba39ca60a4ad3585b67be1b9 Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Wed, 15 Jul 2026 16:40:42 +0000
Subject: [PATCH] Improve edit message validations.

---
 .../api/messages/EnvelopeContentValidator.kt  | 14 +++++--
 .../messages/EnvelopeContentValidatorTest.kt  | 40 +++++++++++++++++++
 2 files changed, 51 insertions(+), 3 deletions(-)

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 6ee8a637f7..59505135f4 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
@@ -67,7 +67,7 @@ object EnvelopeContentValidator {
       content.typingMessage != null -> validateTypingMessage(envelope, content.typingMessage)
       content.decryptionErrorMessage != null -> validateDecryptionErrorMessage(content.decryptionErrorMessage.toByteArray())
       content.storyMessage != null -> validateStoryMessage(content.storyMessage)
-      content.editMessage != null -> validateEditMessage(content.editMessage)
+      content.editMessage != null -> validateEditMessage(envelope, content.editMessage)
       content.pniSignatureMessage != null -> Result.Valid
       content.senderKeyDistributionMessage != null -> Result.Valid
       else -> Result.Invalid("Content is empty!")
@@ -247,7 +247,7 @@ object EnvelopeContentValidator {
       } else if (syncMessage.sent.storyMessageRecipients.isNotEmpty()) {
         Result.Valid
       } else if (syncMessage.sent.editMessage != null) {
-        validateEditMessage(syncMessage.sent.editMessage)
+        validateEditMessage(envelope, syncMessage.sent.editMessage)
       } else {
         Result.Invalid("[SyncMessage] Empty SyncMessage.sent!")
       }
@@ -354,7 +354,7 @@ object EnvelopeContentValidator {
     return Result.Valid
   }
 
-  private fun validateEditMessage(editMessage: EditMessage): Result {
+  private fun validateEditMessage(envelope: Envelope, editMessage: EditMessage): Result {
     if (editMessage.dataMessage == null) {
       return Result.Invalid("[EditMessage] No data message present")
     }
@@ -365,6 +365,14 @@ object EnvelopeContentValidator {
 
     val dataMessage: DataMessage = editMessage.dataMessage
 
+    if (dataMessage.timestamp == null) {
+      return Result.Invalid("[EditMessage] Missing timestamp!")
+    }
+
+    if (dataMessage.timestamp != envelope.clientTimestamp) {
+      return Result.Invalid("[EditMessage] Timestamps don't match! envelope: ${envelope.clientTimestamp}, content: ${dataMessage.timestamp}")
+    }
+
     if (dataMessage.requiredProtocolVersion != null && dataMessage.requiredProtocolVersion > DataMessage.ProtocolVersion.CURRENT.value) {
       return Result.UnsupportedDataMessage(
         ourVersion = DataMessage.ProtocolVersion.CURRENT.value,
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 ac16a214e9..658c311c19 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
@@ -14,6 +14,7 @@ import org.whispersystems.signalservice.internal.push.AttachmentPointer
 import org.whispersystems.signalservice.internal.push.BodyRange
 import org.whispersystems.signalservice.internal.push.Content
 import org.whispersystems.signalservice.internal.push.DataMessage
+import org.whispersystems.signalservice.internal.push.EditMessage
 import org.whispersystems.signalservice.internal.push.Envelope
 import org.whispersystems.signalservice.internal.push.StoryMessage
 import org.whispersystems.signalservice.internal.push.SyncMessage
@@ -656,4 +657,43 @@ class EnvelopeContentValidatorTest {
     val result = EnvelopeContentValidator.validate(Envelope(clientTimestamp = 1234), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
     assert(result is EnvelopeContentValidator.Result.Valid)
   }
+
+  @Test
+  fun `validate - ensure edit message with mismatched nested timestamp is marked invalid`() {
+    val content = Content(
+      editMessage = EditMessage(
+        targetSentTimestamp = 1000,
+        dataMessage = DataMessage(timestamp = 5678)
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(clientTimestamp = 1234), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Invalid)
+  }
+
+  @Test
+  fun `validate - ensure edit message with missing nested timestamp is marked invalid`() {
+    val content = Content(
+      editMessage = EditMessage(
+        targetSentTimestamp = 1000,
+        dataMessage = DataMessage()
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(clientTimestamp = 1234), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Invalid)
+  }
+
+  @Test
+  fun `validate - ensure edit message with nested timestamp matching the envelope is marked valid`() {
+    val content = Content(
+      editMessage = EditMessage(
+        targetSentTimestamp = 1000,
+        dataMessage = DataMessage(timestamp = 1234)
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(clientTimestamp = 1234), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Valid)
+  }
 }