1 files changed, 71 insertions, 0 deletions
diff --git a/backport-CVE-2026-32647.patch b/backport-CVE-2026-32647.patch
new file mode 100644
index 0000000..0a1d23a
--- /dev/null
+++ b/backport-CVE-2026-32647.patch
@@ -0,0 +1,71 @@
+From 7725c372c2fe11ff908b1d6138be219ad694c42f Mon Sep 17 00:00:00 2001
+From: Roman Arutyunyan <arut@nginx.com>
+Date: Sat, 21 Feb 2026 12:04:36 +0400
+Subject: [PATCH] Mp4: avoid zero size buffers in output.
+
+Previously, data validation checks did not cover the cases when the output
+contained empty buffers.  Such buffers are considered illegal and produce
+"zero size buf in output" alerts.  The change rejects the mp4 files which
+produce such alerts.
+
+Also, the change fixes possible buffer overread and overwrite that could
+happen while processing empty stco and co64 atoms, as reported by
+Pavel Kohout (Aisle Research) and Tim Becker.
+---
+ src/http/modules/ngx_http_mp4_module.c | 15 +++++++++------
+ 1 file changed, 9 insertions(+), 6 deletions(-)
+
+diff --git a/src/http/modules/ngx_http_mp4_module.c b/src/http/modules/ngx_http_mp4_module.c
+index 445fab1cdf..173d8ad541 100644
+--- a/src/http/modules/ngx_http_mp4_module.c
++++ b/src/http/modules/ngx_http_mp4_module.c
+@@ -901,8 +901,11 @@ ngx_http_mp4_process(ngx_http_mp4_file_t *mp4)
+         }
+     }
+ 
+-    if (end_offset < start_offset) {
+-        end_offset = start_offset;
++    if (end_offset <= start_offset) {
++        ngx_log_error(NGX_LOG_ERR, mp4->file.log, 0,
++                      "no data between start time and end time in \"%s\"",
++                      mp4->file.name.data);
++        return NGX_ERROR;
+     }
+ 
+     mp4->moov_size += 8;
+@@ -913,7 +916,7 @@ ngx_http_mp4_process(ngx_http_mp4_file_t *mp4)
+ 
+     *prev = &mp4->mdat_atom;
+ 
+-    if (start_offset > mp4->mdat_data.buf->file_last) {
++    if (start_offset >= mp4->mdat_data.buf->file_last) {
+         ngx_log_error(NGX_LOG_ERR, mp4->file.log, 0,
+                       "start time is out mp4 mdat atom in \"%s\"",
+                       mp4->file.name.data);
+@@ -3444,7 +3447,7 @@ ngx_http_mp4_update_stsz_atom(ngx_http_mp4_file_t *mp4,
+     if (data) {
+         entries = trak->sample_sizes_entries;
+ 
+-        if (trak->start_sample > entries) {
++        if (trak->start_sample >= entries) {
+             ngx_log_error(NGX_LOG_ERR, mp4->file.log, 0,
+                           "start time is out mp4 stsz samples in \"%s\"",
+                           mp4->file.name.data);
+@@ -3619,7 +3622,7 @@ ngx_http_mp4_update_stco_atom(ngx_http_mp4_file_t *mp4,
+         return NGX_ERROR;
+     }
+ 
+-    if (trak->start_chunk > trak->chunks) {
++    if (trak->start_chunk >= trak->chunks) {
+         ngx_log_error(NGX_LOG_ERR, mp4->file.log, 0,
+                       "start time is out mp4 stco chunks in \"%s\"",
+                       mp4->file.name.data);
+@@ -3834,7 +3837,7 @@ ngx_http_mp4_update_co64_atom(ngx_http_mp4_file_t *mp4,
+         return NGX_ERROR;
+     }
+ 
+-    if (trak->start_chunk > trak->chunks) {
++    if (trak->start_chunk >= trak->chunks) {
+         ngx_log_error(NGX_LOG_ERR, mp4->file.log, 0,
+                       "start time is out mp4 co64 chunks in \"%s\"",
+                       mp4->file.name.data);