Headline

GHSA-pj86-cfqh-vqx6: express improperly controls modification of query properties

Impact

when using the extended query parser in express ('query parser': 'extended'), the request.query object inherits all object prototype properties, but these properties can be overwritten by query string parameter keys that match the property names

[!IMPORTANT]
the extended query parser is the default in express 4; this was changed in express 5 which by default uses the simple query parser

Patches

the issue has been patched to ensure request.query is a plain object so request.query no longer has object prototype properties. this brings the default behavior of extended query parsing in line with express’s default simple query parser

Workaround

this only impacts users using extended query parsing ('query parser': 'extended'), which is the default in express 4, but not express 5. all users are encouraged to upgrade to the patched versions, but can otherwise work around this issue:

provide `qs` directly and specify `plainObjects: true`

app.set('query parser',
  function (str) {
    return qs.parse(str, {
      plainObjects: true
  });
});

3 days ago

ghsa

Open in Source

#js #git #perl

Impact

when using the extended query parser in express ('query parser’: ‘extended’), the request.query object inherits all object prototype properties, but these properties can be overwritten by query string parameter keys that match the property names

Important

the extended query parser is the default in express 4; this was changed in express 5 which by default uses the simple query parser

Patches

the issue has been patched to ensure request.query is a plain object so request.query no longer has object prototype properties. this brings the default behavior of extended query parsing in line with express’s default simple query parser

Workaround

this only impacts users using extended query parsing ('query parser’: ‘extended’), which is the default in express 4, but not express 5. all users are encouraged to upgrade to the patched versions, but can otherwise work around this issue:

provide qs directly and specify plainObjects: true

app.set('query parser’, function (str) { return qs.parse(str, { plainObjects: true }); });

References