diff -ur icu.org/source/extra/scrptrun/scrptrun.cpp icu/source/extra/scrptrun/scrptrun.cpp
--- icu.org/source/extra/scrptrun/scrptrun.cpp 2017-01-20 01:20:31.000000000 +0100
+++ icu/source/extra/scrptrun/scrptrun.cpp 2017-04-21 22:59:31.708037770 +0200
@@ -151,7 +151,11 @@
         // characters above it on the stack will be poped.
         if (pairIndex >= 0) {
             if ((pairIndex & 1) == 0) {
-                parenStack[++parenSP].pairIndex = pairIndex;
+                ++parenSP;
+                int32_t nVecSize = parenStack.size();
+                if (parenSP == nVecSize)
+                    parenStack.resize(nVecSize + 128);
+                parenStack[parenSP].pairIndex = pairIndex;
                 parenStack[parenSP].scriptCode  = scriptCode;
             } else if (parenSP >= 0) {
                 int32_t pi = pairIndex & ~1;
@@ -185,7 +189,14 @@
             // pop it from the stack
             if (pairIndex >= 0 && (pairIndex & 1) != 0 && parenSP >= 0) {
                 parenSP -= 1;
-                startSP -= 1;
+                /* decrement startSP only if it is >= 0,
+                   decrementing it unnecessarily will lead to memory corruption
+                   while processing the above while block.
+                   e.g. startSP = -4 , parenSP = -1
+                */
+                if (startSP >= 0) {
+                    startSP -= 1;
+                }
             }
         } else {
             // if the run broke on a surrogate pair,
diff -ur icu.org/source/extra/scrptrun/scrptrun.h icu/source/extra/scrptrun/scrptrun.h
--- icu.org/source/extra/scrptrun/scrptrun.h 2017-01-20 01:20:31.000000000 +0100
+++ icu/source/extra/scrptrun/scrptrun.h 2017-04-21 22:59:31.708037770 +0200
@@ -19,6 +19,7 @@
 #include "unicode/utypes.h"
 #include "unicode/uobject.h"
 #include "unicode/uscript.h"
+#include <vector>
 
 U_NAMESPACE_BEGIN
 
@@ -81,7 +82,7 @@
     int32_t scriptEnd;
     UScriptCode scriptCode;
 
-    ParenStackEntry parenStack[128];
+    std::vector<ParenStackEntry> parenStack;
     int32_t parenSP;
 
     static int8_t highBit(int32_t value);
@@ -135,6 +136,7 @@
     scriptEnd   = charStart;
     scriptCode  = USCRIPT_INVALID_CODE;
     parenSP     = -1;
+    parenStack.resize(128);
 }
 
 inline void ScriptRun::reset(int32_t start, int32_t length)