=== modified file 'src/com/mysql/jdbc/EscapeTokenizer.java'
--- src/com/mysql/jdbc/EscapeTokenizer.java	2008-10-20 22:29:45 +0000
+++ src/com/mysql/jdbc/EscapeTokenizer.java	2009-02-09 21:03:05 +0000
@@ -108,11 +108,13 @@
 				if (this.inQuotes && c == quoteChar) {
 					if (this.pos + 1 < this.sourceLength) {
 						if (this.source.charAt(this.pos + 1) == quoteChar) {
-							// Doubled-up quote escape
-							tokenBuf.append(quoteChar);
-							tokenBuf.append(quoteChar);
-							this.pos++;
-							continue;
+							// Doubled-up quote escape, if the first quote isn't already escaped
+							if (this.lastChar != '\\') {
+								tokenBuf.append(quoteChar);
+								tokenBuf.append(quoteChar);
+								this.pos++;
+								continue;
+							}
 						}
 					}
 				}

=== modified file 'src/testsuite/regression/StatementRegressionTest.java'
--- src/testsuite/regression/StatementRegressionTest.java	2009-02-02 17:00:13 +0000
+++ src/testsuite/regression/StatementRegressionTest.java	2009-02-09 21:05:48 +0000
@@ -5825,4 +5825,18 @@
 			closeMemberJDBCResources();
 		}
 	}
+	
+	/**
+	 * Bug #42253 - multiple escaped quotes cause exception from EscapeProcessor.
+	 */
+	public void testBug42253() throws Exception {
+		try {
+			rs = stmt.executeQuery("select '\\'\\'','{t\\'}'");
+			rs.next();
+			assertEquals("''", rs.getString(1));
+			assertEquals("{t'}", rs.getString(2));
+		} finally {
+			closeMemberJDBCResources();
+		}
+	}
  } 
\ No newline at end of file