value in a $literal expression can trigger an expression parse assertion causing an aggregation to fail

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    • Type: Improvement
    • Resolution: Won't Fix
    • Priority: Major - P3
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    • Affects Version/s: None
    • Component/s: Aggregation Framework
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      Observed behavior: A $literal value may be parsed as a FieldPath, triggering an exception if it represents an invalid FieldPath. This will allow a $literal field supplied by a malicious user to cause an aggregation query to fail with an assertion.
      Expected behavior: A $literal value is not parsed as an expression and is handled as a string literal.

      c = db.c;
      c.drop();
      c.save( { prefix:'moon' } );
      
      // This is a safe literal.
      suffix = 'beam';
      
      printjson( c.aggregate( { $project:{ word:{ $add:[ '$prefix', { $literal:suffix } ] } } } ) );
      
      // This literal is parsed as a FieldPath with adjacent dots, which is not allowed.
      suffix = '$hine..';
      
      printjson( c.aggregate( { $project:{ word:{ $add:[ '$prefix', { $literal:suffix } ] } } } ) );
      

            Assignee:
            Matt Dannenberg (Inactive)
            Reporter:
            Aaron Staple (Inactive)
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              Created:
              Updated:
              Resolved: