diff --git a/third_party/libopenjpeg20/jp2.c b/third_party/libopenjpeg20/jp2.c
index 1fa607d66..78a2d22ff 100644
--- a/third_party/libopenjpeg20/jp2.c
+++ b/third_party/libopenjpeg20/jp2.c
@@ -1049,6 +1049,14 @@ static OPJ_BOOL opj_jp2_apply_pclr(opj_image_t *image,
     }
 
     old_comps = image->comps;
+    /* Overflow check: prevent integer overflow */
+    for (i = 0; i < nr_channels; ++i) {
+      cmp = cmap[i].cmp;
+      if (old_comps[cmp].h == 0 || old_comps[cmp].w > ((OPJ_UINT32)-1) / sizeof(OPJ_INT32) / old_comps[cmp].h) {
+        return OPJ_FALSE;
+      }
+    }
+
     new_comps = (opj_image_comp_t*)
                 opj_malloc(nr_channels * sizeof(opj_image_comp_t));
     if (!new_comps) {
@@ -1093,21 +1101,27 @@ static OPJ_BOOL opj_jp2_apply_pclr(opj_image_t *image,
         cmp = cmap[i].cmp;
         pcol = cmap[i].pcol;
         src = old_comps[cmp].data;
-        assert(src); /* verified above */
+        dst = new_comps[i].data;
         max = new_comps[i].w * new_comps[i].h;
 
+        /* Prevent null pointer access */
+        if (!src || !dst) {
+          for (j = 0; j < nr_channels; ++j) {
+            opj_free(new_comps[j].data);
+          }
+          opj_free(new_comps);
+          new_comps = NULL;
+          return OPJ_FALSE;
+        }
+
         /* Direct use: */
         if (cmap[i].mtyp == 0) {
             assert( cmp == 0 ); // probably wrong.
-            dst = new_comps[i].data;
-            assert(dst);
             for (j = 0; j < max; ++j) {
                 dst[j] = src[j];
             }
         } else {
             assert( i == pcol ); // probably wrong?
-            dst = new_comps[i].data;
-            assert(dst);
             for (j = 0; j < max; ++j) {
                 /* The index */
                 if ((k = src[j]) < 0) {