diff --git a/CHANGELOG.md b/CHANGELOG.md
index ce5fc79c..7accf389 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,9 +1,11 @@
 # Changelog
 
-## [1.6.15] — unreleased
+## [1.7.0] — 2026-09-02
 
 ### Fixed
 
+- `mux/mp4`: the capped child-box scan treated any `size < 8` as a stop, which dropped a 64-bit `largesize` child box (`size == 1`, real length in the following 8 bytes) and every sibling after it; a `size == 0` (run-to-end) box was mishandled too. Both are now honoured, so an MP4/MOV whose boxes use 64-bit sizes is walked fully instead of truncated.
+
 - Linux: `SgIoTransport::raw_command` clamped an over-length CDB with `cdb.len().min(16)` instead of routing it through the shared `checked_cdb_len` guard that `execute()` uses. Under SPC-4 a CDB's length is fixed by its opcode, so truncating one does not shorten the command — it sends a descriptor the drive will read as something else. An empty CDB was likewise unguarded, and went to the sg driver as a zero-length command descriptor. Unreachable — `raw_command` is private and its one caller passes a fixed 6-byte ALLOW MEDIUM REMOVAL — but it was the one transport path that did the thing the guard exists to prevent.
 - Linux: the fd hand-off between a background recovery thread and `SgIoTransport::drop` had no release edge, so a recovery thread that published its fd after teardown had drained the slot was not guaranteed to observe `dead == true` and could leave the descriptor unclosed. `Drop`'s claiming `swap` was `Acquire` (a relaxed store, heading no release sequence) and the recovery thread's `compare_exchange` was `Release` (a relaxed load, acquiring nothing) — neither side alone was enough, and upgrading only one still leaks. Both are now `AcqRel`. Worst case was a leaked file descriptor on a transport already being torn down.
 
diff --git a/Cargo.toml b/Cargo.toml
index 78feb441..db01577a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "libfreemkv"
-version = "1.6.14"
+version = "1.7.0"
 edition = "2024"
 rust-version = "1.88"
 license = "MIT"
diff --git a/src/mux/mp4/read.rs b/src/mux/mp4/read.rs
index 6440b0af..3299fb3a 100644
--- a/src/mux/mp4/read.rs
+++ b/src/mux/mp4/read.rs
@@ -426,7 +426,7 @@ fn find_boxes_capped<'a>(payload: &'a [u8], want: &[u8; 4], cap: usize) -> Vec<&
     let mut out = Vec::new();
     let mut pos = 0;
     while pos + 8 <= payload.len() && out.len() < cap {
-        let size = u32::from_be_bytes([
+        let size32 = u32::from_be_bytes([
             payload[pos],
             payload[pos + 1],
             payload[pos + 2],
@@ -438,13 +438,36 @@ fn find_boxes_capped<'a>(payload: &'a [u8], want: &[u8; 4], cap: usize) -> Vec<&
             payload[pos + 6],
             payload[pos + 7],
         ];
-        if size < 8 || pos + size > payload.len() {
+        // ISO/IEC 14496-12 §4.2: size==1 → 64-bit largesize after the type
+        // (16-byte header); size==0 → box runs to the payload end. The child
+        // scan must honour both or a largesize sibling ends the walk early.
+        let (box_size, header_len) = match size32 {
+            1 => {
+                if pos + 16 > payload.len() {
+                    break;
+                }
+                let large = u64::from_be_bytes([
+                    payload[pos + 8],
+                    payload[pos + 9],
+                    payload[pos + 10],
+                    payload[pos + 11],
+                    payload[pos + 12],
+                    payload[pos + 13],
+                    payload[pos + 14],
+                    payload[pos + 15],
+                ]) as usize;
+                (large, 16usize)
+            }
+            0 => (payload.len() - pos, 8usize),
+            n => (n, 8usize),
+        };
+        if box_size < header_len || pos + box_size > payload.len() {
             break;
         }
         if &bt == want {
-            out.push(&payload[pos + 8..pos + size]);
+            out.push(&payload[pos + header_len..pos + box_size]);
         }
-        pos += size;
+        pos += box_size;
     }
     out
 }
@@ -998,6 +1021,28 @@ mod tests {
         }
     }
 
+    // Regression: a child box in the 64-bit largesize form (size==1) must not
+    // stop the sibling walk — old code saw size 1 < 8 and broke, so every box
+    // after it (here `moov`) vanished and its track was silently dropped.
+    #[test]
+    fn find_box_walks_past_a_largesize_sibling() {
+        let mut payload = Vec::new();
+        // `free` as an empty largesize box: size32=1, u64 total size = 16.
+        payload.extend_from_slice(&1u32.to_be_bytes());
+        payload.extend_from_slice(b"free");
+        payload.extend_from_slice(&16u64.to_be_bytes());
+        // `moov` (32-bit) with a 4-byte payload immediately after it.
+        payload.extend_from_slice(&12u32.to_be_bytes());
+        payload.extend_from_slice(b"moov");
+        payload.extend_from_slice(&[0xDE, 0xAD, 0xBE, 0xEF]);
+
+        assert_eq!(
+            find_box(&payload, b"moov"),
+            Some(&[0xDEu8, 0xAD, 0xBE, 0xEF][..]),
+            "moov after a largesize `free` sibling must still be found",
+        );
+    }
+
     // Positive-path test for `parse_stss`: two distinct entries in a buffer
     // sized to exactly fit them, catching offset/stride arithmetic mutants.
     // See docs/mp4-read.md — parse_stss_reads_two_distinct_entries.