diff --git a/app/src/main/java/com/bitchat/android/mesh/AnnouncementIdentityValidator.kt b/app/src/main/java/com/bitchat/android/mesh/AnnouncementIdentityValidator.kt
index 89b833b14..dfe146e5e 100644
--- a/app/src/main/java/com/bitchat/android/mesh/AnnouncementIdentityValidator.kt
+++ b/app/src/main/java/com/bitchat/android/mesh/AnnouncementIdentityValidator.kt
@@ -8,7 +8,11 @@ import com.bitchat.android.util.toHexString
 
 /** Canonical, side-effect-free preflight for a self-signed mesh announcement. */
 object AnnouncementIdentityValidator {
-    private const val MAX_CLOCK_SKEW_MS = 10 * 60 * 1_000L
+    /**
+     * Clock skew tolerated on a signed announcement. Shared with [SecurityManager] so no packet
+     * type is held to a stricter future bound than the announcement that admits the peer.
+     */
+    internal const val MAX_CLOCK_SKEW_MS = 10 * 60 * 1_000L
 
     fun verify(
         packet: BitchatPacket,
diff --git a/app/src/main/java/com/bitchat/android/mesh/SecurityManager.kt b/app/src/main/java/com/bitchat/android/mesh/SecurityManager.kt
index 3f6846792..f392277e9 100644
--- a/app/src/main/java/com/bitchat/android/mesh/SecurityManager.kt
+++ b/app/src/main/java/com/bitchat/android/mesh/SecurityManager.kt
@@ -57,6 +57,29 @@ class SecurityManager(private val encryptionService: EncryptionService, private
         val currentTime = System.currentTimeMillis()
         val messageType = MessageType.fromValue(packet.type)
 
+        // A signed packet's timestamp is authenticated as the sender's choice, not sanity-checked,
+        // and it survives into every downstream ordering decision. GossipSyncManager builds its
+        // sync filter from `sortByDescending { it.timestamp }`, so future-dated broadcasts take
+        // every advertised slot and crowd real traffic out of gossip sync across the mesh; the
+        // public timeline orders on the same field. Only ANNOUNCE was bounded, in
+        // AnnouncementIdentityValidator.
+        //
+        // Bound the future direction for every type, at the same allowance that admits the peer's
+        // announcement — a device skewed further than this already cannot be verified, so nothing
+        // that works today starts failing. The past stays open: store-and-forward replays packets
+        // cached for up to twelve hours.
+        val nowForSkew = currentTime.coerceAtLeast(0).toULong()
+        if (packet.timestamp > nowForSkew &&
+            packet.timestamp - nowForSkew >
+            AnnouncementIdentityValidator.MAX_CLOCK_SKEW_MS.toULong()
+        ) {
+            Log.w(
+                TAG,
+                "Dropping future-dated ${messageType?.name ?: packet.type} from $peerID"
+            )
+            return false
+        }
+
         // LEAVE mutates presence immediately and cannot be safely replayed after the in-memory
         // duplicate cache expires (or after an app restart). Bound it to the same five-minute
         // security window used for duplicate retention while tolerating symmetric clock skew.
diff --git a/app/src/test/kotlin/com/bitchat/android/mesh/SecurityManagerTest.kt b/app/src/test/kotlin/com/bitchat/android/mesh/SecurityManagerTest.kt
index 2a56e708b..324fcfd0c 100644
--- a/app/src/test/kotlin/com/bitchat/android/mesh/SecurityManagerTest.kt
+++ b/app/src/test/kotlin/com/bitchat/android/mesh/SecurityManagerTest.kt
@@ -276,6 +276,81 @@ class SecurityManagerTest {
         assertFalse("Future-dated LEAVE must not extend its replay lifetime", securityManager.validatePacket(future, otherPeerID))
     }
 
+    private fun signedMessage(offsetMs: Long): BitchatPacket = BitchatPacket(
+        type = MessageType.MESSAGE.value,
+        ttl = 7u,
+        senderID = MeshPacketUtils.hexStringToByteArray(otherPeerID),
+        timestamp = (System.currentTimeMillis() + offsetMs).toULong(),
+        payload = dummyPayload
+    ).also { it.signature = validSignature }
+
+    @Test
+    fun `validatePacket rejects future-dated broadcast messages`() {
+        setupKnownPeer(otherPeerID, otherSigningKey)
+
+        // GossipSyncManager advertises the newest packets first, so a future-dated broadcast
+        // takes a sync slot permanently and crowds real traffic out across the mesh.
+        val future = signedMessage(AnnouncementIdentityValidator.MAX_CLOCK_SKEW_MS + 60_000L)
+
+        assertFalse(
+            "A signed but future-dated MESSAGE must not be admitted",
+            securityManager.validatePacket(future, otherPeerID)
+        )
+    }
+
+    @Test
+    fun `validatePacket admits messages inside the announcement clock-skew allowance`() {
+        setupKnownPeer(otherPeerID, otherSigningKey)
+
+        // A peer skewed further than this cannot get its ANNOUNCE accepted either, so the bound
+        // must not be tighter than the one that admits the peer in the first place.
+        val skewed = signedMessage(AnnouncementIdentityValidator.MAX_CLOCK_SKEW_MS - 60_000L)
+
+        assertTrue(
+            "A tolerable forward clock skew must still deliver",
+            securityManager.validatePacket(skewed, otherPeerID)
+        )
+    }
+
+    @Test
+    fun `validatePacket still admits old messages for store and forward`() {
+        setupKnownPeer(otherPeerID, otherSigningKey)
+
+        // StoreForward caches for 12 hours; bounding the past would silently drop that replay.
+        val old = signedMessage(-6 * 60 * 60 * 1_000L)
+
+        assertTrue(
+            "Store-and-forward replay must keep working",
+            securityManager.validatePacket(old, otherPeerID)
+        )
+    }
+
+    @Test
+    fun `validatePacket rejects future-dated packets of every relayed type`() {
+        setupKnownPeer(otherPeerID, otherSigningKey)
+
+        val futureOffset = AnnouncementIdentityValidator.MAX_CLOCK_SKEW_MS + 60_000L
+        listOf(
+            MessageType.MESSAGE,
+            MessageType.FILE_TRANSFER,
+            MessageType.VOICE_FRAME,
+            MessageType.FRAGMENT
+        ).forEach { type ->
+            val packet = BitchatPacket(
+                type = type.value,
+                ttl = 7u,
+                senderID = MeshPacketUtils.hexStringToByteArray(otherPeerID),
+                timestamp = (System.currentTimeMillis() + futureOffset).toULong(),
+                payload = dummyPayload
+            ).also { it.signature = validSignature }
+
+            assertFalse(
+                "${type.name} must not be admitted with a future timestamp",
+                securityManager.validatePacket(packet, otherPeerID)
+            )
+        }
+    }
+
     @Test
     fun `validatePacket - accepts ANNOUNCE packet from unknown peer (extracts key)`() {
         val announcement = IdentityAnnouncement(