diff --git a/ext/misc/fossildelta.c b/ext/misc/fossildelta.c
index 269d9d84fb..084665741b 100644
--- a/ext/misc/fossildelta.c
+++ b/ext/misc/fossildelta.c
@@ -566,8 +566,8 @@ static int delta_apply(
     /* ERROR: size integer not terminated by "\n" */
     return -1;
   }
-  zDelta++; lenDelta--;
-  while( lenDelta>0 && *zDelta ){
+  zDelta++; lenDelta--; /* Skip the \n */
+  while( lenDelta>0 && zDelta[0] ){
     unsigned int cnt, ofst;
     cnt = deltaGetInt(&zDelta, &lenDelta);
     if( lenDelta<=0 ) return -1;
diff --git a/ext/rbu/rbu8.test b/ext/rbu/rbu8.test
index b73bde274c..73de3d17e2 100644
--- a/ext/rbu/rbu8.test
+++ b/ext/rbu/rbu8.test
@@ -68,5 +68,27 @@ do_execsql_test 1.3.2 {
 }
 integrity_check 1.3.3
 
+#-------------------------------------------------------------------------
+# Test for a problem in rbuDeltaApply().
+# Bug report: https://sqlite.org/bugs/forumpost/8123aba97f
+reset_db
+forcedelete rbu.db
+
+do_execsql_test 2.0 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b BLOB);
+  INSERT INTO t1 VALUES(10, X'0102030405');
+}
+db close
+sqlite3 db rbu.db
+do_execsql_test 2.1 {
+  CREATE TABLE data_t1(a INTEGER PRIMARY KEY, b BLOB, rbu_control);
+  INSERT INTO data_t1 VALUES(10, X'410A353A11223344553540302C3B', '.f');
+}
+
+do_test 2.2 {
+  sqlite3rbu rbu test.db rbu.db
+  while {[rbu step]=="SQLITE_OK"} {}
+  list [catch { rbu close } msg] $msg
+} {0 SQLITE_DONE}
 
 finish_test
diff --git a/ext/rbu/rbucorrupt.test b/ext/rbu/rbucorrupt.test
new file mode 100644
index 0000000000..0f9841e638
--- /dev/null
+++ b/ext/rbu/rbucorrupt.test
@@ -0,0 +1,61 @@
+# 2026 July 6
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+
+source [file join [file dirname [info script]] rbu_common.tcl]
+if_no_rbu_support { finish_test ; return }
+set ::testprefix rbucorrupt
+
+forcedelete rbu.db
+forcedelete state.db
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(id INTEGER PRIMARY KEY, a, b);
+  WITH s(i) AS (
+    SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<63
+  )
+  INSERT INTO t1 SELECT i, i*10, 'row'||i FROM s;
+}
+
+sqlite3 db rbu.db 
+do_execsql_test 1.1 {
+  CREATE TABLE data_t1(id INTEGER PRIMARY KEY, a, b, rbu_control);
+  WITH s(i) AS (
+    SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<63
+  )
+  INSERT INTO data_t1 SELECT i, i*100, NULL, '.x.' FROM s;
+}
+
+db close
+
+do_test 1.2 {
+  sqlite3rbu rbu test.db rbu.db state.db
+  while {[rbu step]=="SQLITE_OK"} {
+    set st [rbu state]
+    if {$st=="checkpoint"} break
+  }
+  rbu close
+} {SQLITE_OK}
+
+do_test 1.3 {
+  sqlite3 db state.db 
+  db eval { UPDATE rbu_state SET v=-1 WHERE k=4 }
+  db close
+} {}
+
+do_test 1.4 {
+  sqlite3rbu rbu test.db rbu.db state.db
+  rbu step
+  list [catch { rbu close } msg] $msg
+} {1 SQLITE_CORRUPT}
+
+
+finish_test
diff --git a/ext/rbu/sqlite3rbu.c b/ext/rbu/sqlite3rbu.c
index ee3d8df68c..1629acfff1 100644
--- a/ext/rbu/sqlite3rbu.c
+++ b/ext/rbu/sqlite3rbu.c
@@ -604,8 +604,8 @@ static int rbuDeltaApply(
   int lenDelta,          /* Length of the delta */
   char *zOut             /* Write the output into this preallocated buffer */
 ){
-  unsigned int limit;
-  unsigned int total = 0;
+  sqlite3_uint64 limit;
+  sqlite3_uint64 total = 0;
 #if RBU_ENABLE_DELTA_CKSUM
   char *zOrigOut = zOut;
 #endif
@@ -615,8 +615,8 @@ static int rbuDeltaApply(
     /* ERROR: size integer not terminated by "\n" */
     return -1;
   }
-  zDelta++; lenDelta--;
-  while( lenDelta>0 && *zDelta ){
+  zDelta++; lenDelta--; /* Skip the \n */
+  while( lenDelta>0 && zDelta[0] ){
     unsigned int cnt, ofst;
     cnt = rbuDeltaGetInt(&zDelta, &lenDelta);
     if( lenDelta<=0 ) return -1;
@@ -624,7 +624,7 @@ static int rbuDeltaApply(
       case '@': {
         zDelta++; lenDelta--;
         ofst = rbuDeltaGetInt(&zDelta, &lenDelta);
-        if( lenDelta>0 || zDelta[0]!=',' ){
+        if( lenDelta>0 && zDelta[0]!=',' ){
           /* ERROR: copy command not terminated by ',' */
           return -1;
         }
@@ -649,7 +649,7 @@ static int rbuDeltaApply(
           /* ERROR:  insert command gives an output larger than predicted */
           return -1;
         }
-        if( (i64)cnt>(i64)lenDelta ){
+        if( cnt>lenDelta ){
           /* ERROR: insert count exceeds size of delta */
           return -1;
         }
@@ -2758,6 +2758,9 @@ static RbuState *rbuLoadState(sqlite3rbu *p){
 
       case RBU_STATE_ROW:
         pRet->nRow = sqlite3_column_int(pStmt, 1);
+        if( pRet->nRow<0 ){
+          rc = SQLITE_CORRUPT;
+        }
         break;
 
       case RBU_STATE_PROGRESS:
diff --git a/manifest b/manifest
index 7469b1f6a2..3849ceac59 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Avoid\sa\s(harmless)\s1-byte\sOOB\sread\sdue\sto\smalformed\sinputs\sin\sthe\nnormalize.c\sextension.
-D 2026-07-06T13:57:07.357
+C Fix\smulutiple\sproblems\sin\sRBU\sand\sreduce\sdivergence\sbetween\sthe\sFossil\nnative\simplementation\sof\sdelta\sand\sthe\svariant\sof\sthat\scode\sused\sby\sRBU.
+D 2026-07-06T16:46:25.117
 F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@ -377,7 +377,7 @@ F ext/misc/decimal.c 4168943bb0f605058167fc13a3219625f014cb9d30d9c1aed5ecf55e00a
 F ext/misc/eval.c 04bc9aada78c888394204b4ed996ab834b99726fb59603b0ee3ed6e049755dc1
 F ext/misc/explain.c 04c9270fd8cf93a9bceb12d2f5f67e3f09a4e58b3e0efe14d24531444d2fffdf
 F ext/misc/fileio.c 8192f52608ab25f1976c8997775083e2655cb94ff9d194b7b5923b5470d6ce65
-F ext/misc/fossildelta.c eb6a6e11c4aff4a081bfe4d0069e2dc054e1f9005336b6b511c43faf406051ed
+F ext/misc/fossildelta.c 090a0a02a685363710572eea6d1fb346ee377cf5cecdf2fbe038764a8789041f
 F ext/misc/fuzzer.c 32cef9a29864a1bc1329ccb6dfa613f197bb83491a7612c2ca2c83ee26cd8f14
 F ext/misc/ieee754.c 2901d08a586d00a1d3c0fd89e03c57ee9e2b5f013b0daab9e49c7a48a9d5946b
 F ext/misc/memstat.c 03ab52d2d841eb3f55118105c1964d5225f152b23bd708844c648b48d14ccbcf
@@ -435,7 +435,7 @@ F ext/rbu/rbu3.test 4a81517af618c3bf8c72e2d0b81c7c06acb8d176036d63d8e6669b733423
 F ext/rbu/rbu5.test e21820b83822ae4c12afc2078a7b6c0523fb0cefe69c8b23c044cea91359e81c
 F ext/rbu/rbu6.test db2ff1f832dfc9e34c7910b17e157c2fe0e36024a3fe1119dd6437640dc07c82
 F ext/rbu/rbu7.test 5fa41734613a3ae1bb93d280eb3c341cff5dcc72652ff9ec7fbaa12425eda9c2
-F ext/rbu/rbu8.test 93d45824dab8f68872b6d22acc787ab18ba92ef0fa0d430be37653d0246c7a0d
+F ext/rbu/rbu8.test 057c9e074a6d7b7c3038d5a14a2f1e0d753c870aefbf3a48d20594a5049547fc
 F ext/rbu/rbu9.test 4b66f0705442711a44b54ef2cc3c59952f1ea15f12e34442681bdb1a6eb33065
 F ext/rbu/rbuA.test 3f8fdd4ae7b9a0571af7361cd88359254f63e445ac4acfe395173e31d7e3fc31
 F ext/rbu/rbuB.test c639803bbc1dc9358afe6abe046dc4d3e9965238b75239b04e3a8e33e3e90f85
@@ -443,6 +443,7 @@ F ext/rbu/rbuC.test 5326ea3954754c68fd518beb70d3e6b6690af53e1a5fa102d650e4110b26
 F ext/rbu/rbu_common.tcl 15d063397a89aeaf26b4cbdf6f29911b4154a902ba61a40c4f180ab452454a63
 F ext/rbu/rbubusy.test 88298187ad35aac9084436d85ca66b3722f96eaa704a09cfe5f931d452ab7237
 F ext/rbu/rbucollate.test 9852ec5e5ba7f3b04ce849a24ef7298e03ae0f16e58e6031d0f845234559feec
+F ext/rbu/rbucorrupt.test 289363dc1a66362368925cffce90d781dc8ac49f85943b2618027bf830bb9d7e
 F ext/rbu/rbucrash.test d2b5d619d9281c89cad74401b73b46172daa89906940b1d739c813ddc0cd2cf5
 F ext/rbu/rbucrash2.test 0a1a72223d880215ce2893a3260320c31a9358d23cb124c610e4f0d984a93285
 F ext/rbu/rbudiff.test 8b8b8b569c68fc880134e0fac4bf6b4b7a907aea4cc6eacf7e1d45e1d47b6aac
@@ -468,7 +469,7 @@ F ext/rbu/rbuvacuum.test 542561741ff2b262e3694bc6012b44694ee62c545845319a06f3237
 F ext/rbu/rbuvacuum2.test 1a9bd41f127be2826de2a65204df9118525a8af8d16e61e6bc63ba3ac0010a23
 F ext/rbu/rbuvacuum3.test 3ce42695fdf21aaa3499e857d7d4253bc499ad759bcd6c9362042c13cd37d8de
 F ext/rbu/rbuvacuum4.test ffccd22f67e2d0b380d2889685742159dfe0d19a3880ca3d2d1d69eefaebb205
-F ext/rbu/sqlite3rbu.c d8c28bb8715718be354f4e283cc03533ba03c8f56e2dc39d9ba4d466428c3dcf
+F ext/rbu/sqlite3rbu.c c26e6638c4e02260a07058c85e710d1e25b0c05f5dfeb74aa0c3c23b88dfe5d0
 F ext/rbu/sqlite3rbu.h e3a5bf21e09ca93ce4e8740e00d6a853e90a697968ec0ea98f40826938bdb68e
 F ext/rbu/test_rbu.c 8b6e64e486c28c41ef29f6f4ea6be7b3091958987812784904f5e903f6b56418
 F ext/recover/dbdata.c 10d3c56968a9af6853722a47280805ad1564714d79ea45ac6f7da14bb57fd137
@@ -2203,9 +2204,11 @@ F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee
 F tool/warnings.sh a554d13f6e5cf3760f041b87939e3d616ec6961859c3245e8ef701d1eafc2ca2
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
 F tool/winmain.c 00c8fb88e365c9017db14c73d3c78af62194d9644feaf60e220ab0f411f3604c
-P 37c90c8fc2d694dabc7c8e7fd49ae2ab46f91f9b88fd7c829b72225881598495
-Q +b1d7123bc619e3cb9dffa8dd52ba31cc18329b14557d8f2d9e547b729016548c
-R 5748c29e130fc76f3982bb3509f7a1d9
+P a6cdeee6e63e3635373d7ecfdefb99b2d607290b4e419dcd37e7eed3e73a5a2c
+Q +0bfba3824f3d4c136db8479c97bd789fa0df7c86ba95bd0f011c569004be2166
+Q +7f49a7a90eda01753c0dff65197bd7bc48a751e24a46919d30af6e2baf0788fc
+Q +9e54159f9a839f7fae3dee348fab862dc4bbe36ab866d0b3927f05fd10b1414a
+R c429e333d3af1f10be634f030c6d03af
 U drh
-Z c9935d1d2869eb8275fdb301de426d01
+Z cc30ca8aa4ccdee80a46828f0ce7c126
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 52604da42b..eb4c2cf734 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-a6cdeee6e63e3635373d7ecfdefb99b2d607290b4e419dcd37e7eed3e73a5a2c
+6870e39ecc3425db7b80432ca4cf5b9f75615f58140192557d18ed6f432f46cd