Index: src/btree.c
==================================================================
--- src/btree.c
+++ src/btree.c
@@ -8724,11 +8724,16 @@
       **
       ** This optimization cannot be used on an autovacuum database if the
       ** new entry uses overflow pages, as the insertCell() call below is
       ** necessary to add the PTRMAP_OVERFLOW1 pointer-map entry.  */
       assert( rc==SQLITE_OK ); /* clearCell never fails when nLocal==nPayload */
-      if( oldCell+szNew > pPage->aDataEnd ) return SQLITE_CORRUPT_BKPT;
+      if( oldCell < pPage->aData+pPage->hdrOffset+10 ){
+        return SQLITE_CORRUPT_BKPT;
+      }
+      if( oldCell+szNew > pPage->aDataEnd ){
+        return SQLITE_CORRUPT_BKPT;
+      }
       memcpy(oldCell, newCell, szNew);
       return SQLITE_OK;
     }
     dropCell(pPage, idx, info.nSize, &rc);
     if( rc ) goto end_insert;

Index: test/fuzzdata7.db
==================================================================
--- test/fuzzdata7.db
+++ test/fuzzdata7.db
cannot compute difference between binary files