diff --git a/htdocs/core/db/mssql.class.php b/htdocs/core/db/mssql.class.php
index efffd5059c6..3a5060e856e 100644
--- a/htdocs/core/db/mssql.class.php
+++ b/htdocs/core/db/mssql.class.php
@@ -419,7 +419,11 @@ class DoliDBMssql extends DoliDB
 		}
 		//print "<!--".$query."-->";
 
-		if (! in_array($query, array('BEGIN','COMMIT','ROLLBACK'))) dol_syslog('sql='.$query, LOG_DEBUG);
+		if (! in_array($query, array('BEGIN','COMMIT','ROLLBACK')))
+		{
+			$SYSLOG_SQL_LIMIT = 10000;	// limit log to 10kb per line to limit DOS attacks
+			dol_syslog('sql='.substr($query, 0, $SYSLOG_SQL_LIMIT), LOG_DEBUG);
+		}
 
 		if (! $this->database_name)
 		{
diff --git a/htdocs/core/db/pgsql.class.php b/htdocs/core/db/pgsql.class.php
index 2777f2d0365..b577ff29bf5 100644
--- a/htdocs/core/db/pgsql.class.php
+++ b/htdocs/core/db/pgsql.class.php
@@ -522,7 +522,11 @@ class DoliDBPgsql extends DoliDB
 			@pg_query($this->db, 'SAVEPOINT mysavepoint');
 		}
 
-		if (! in_array($query, array('BEGIN','COMMIT','ROLLBACK'))) dol_syslog('sql='.$query, LOG_DEBUG);
+		if (! in_array($query, array('BEGIN','COMMIT','ROLLBACK')))
+		{
+			$SYSLOG_SQL_LIMIT = 10000;	// limit log to 10kb per line to limit DOS attacks
+			dol_syslog('sql='.substr($query, 0, $SYSLOG_SQL_LIMIT), LOG_DEBUG);
+		}
 
 		$ret = @pg_query($this->db, $query);
 
diff --git a/htdocs/core/db/sqlite3.class.php b/htdocs/core/db/sqlite3.class.php
index 360b72f80d9..24bb679f17b 100644
--- a/htdocs/core/db/sqlite3.class.php
+++ b/htdocs/core/db/sqlite3.class.php
@@ -453,7 +453,11 @@ class DoliDBSqlite3 extends DoliDB
         }
         //print "After convertSQLFromMysql:\n".$query."<br>\n";
 
-        if (! in_array($query, array('BEGIN','COMMIT','ROLLBACK'))) dol_syslog('sql='.$query, LOG_DEBUG);
+        if (! in_array($query, array('BEGIN','COMMIT','ROLLBACK')))
+        {
+        	$SYSLOG_SQL_LIMIT = 10000;	// limit log to 10kb per line to limit DOS attacks
+        	dol_syslog('sql='.substr($query, 0, $SYSLOG_SQL_LIMIT), LOG_DEBUG);
+        }
         if (empty($query)) return false;    // Return false = error if empty request
 
         // Ordre SQL ne necessitant pas de connexion a une base (exemple: CREATE DATABASE)