diff --git a/manifest b/manifest
index 130891347d..40efb1825c 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sa\sharmless\scompiler\swarning\sin\sSessions.
-D 2018-12-14T13:47:17.713
+C Avoid\sa\sbuffer\soverread\sin\sptrmapPutOvflPtr()\sthat\scan\soccurs\sin\sa\ncorrupt\sdatabase\sfile\sthat\shas\slarge\sentries\sand\suses\sautovacuum.
+D 2018-12-14T16:00:38.064
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in d8b254f8bb81bab43c340d70d17dc3babab40fcc8a348c8255881f780a45fee6
@@ -448,7 +448,7 @@ F src/auth.c 0fac71038875693a937e506bceb492c5f136dd7b1249fbd4ae70b4e8da14f9df
 F src/backup.c 78d3cecfbe28230a3a9a1793e2ead609f469be43e8f486ca996006be551857ab
 F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c 89e9abe6a3f7461c8c5d44314b261e1dd29a31557d1dd91c72378bc0976fc1f6
+F src/btree.c af1055a0a69a4a299d0095a0e0b3386c942ddf9b158098c6d64fe1c93adbeb82
 F src/btree.h febb2e817be499570b7a2e32a9bbb4b607a9234f6b84bb9ae84916d4806e96f2
 F src/btreeInt.h 620ab4c7235f43572cf3ac2ac8723cbdf68073be4d29da24897c7b77dda5fd96
 F src/build.c ef9d7dc73e40dd9d10c28848343e21e8bc1baaab92cfb75eda893fff4fbf6b55
@@ -1787,7 +1787,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 32754ca6f86da8165e274f98f35fc3df3aebd273e9da08387e2d0c3c89abda0f
-R 3d9fe236acd328f6aafabdc7e0f6bbfc
+P fc9791ea987352e3e1322fbb7f833c23b402432af8249f9d397c6f7456788637
+R f5743306f54d784293952b3602df596c
 U drh
-Z ea9bbe01e8202c5233345adba0cefb74
+Z 6e0967960c2e7605bd0b191a56849a10
diff --git a/manifest.uuid b/manifest.uuid
index 0342a084c2..0bc90c32e6 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-fc9791ea987352e3e1322fbb7f833c23b402432af8249f9d397c6f7456788637
\ No newline at end of file
+f8b781cf41800e9f61a1c5376404a97e76a2bbbcaa17396d42be62f731363947
\ No newline at end of file
diff --git a/src/btree.c b/src/btree.c
index 55518bd8a2..9156412922 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -1369,7 +1369,12 @@ static void ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell, int *pRC){
   assert( pCell!=0 );
   pPage->xParseCell(pPage, pCell, &info);
   if( info.nLocal<info.nPayload ){
-    Pgno ovfl = get4byte(&pCell[info.nSize-4]);
+    Pgno ovfl;
+    if( SQLITE_WITHIN(pPage->aDataEnd, pCell, pCell+info.nLocal) ){
+      *pRC = SQLITE_CORRUPT_BKPT;
+      return;
+    }
+    ovfl = get4byte(&pCell[info.nSize-4]);
     ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno, pRC);
   }
 }