github expressjs/express v5.3.0
on GitHub

6 hours ago

Highlights

🐞 Bug fixes

  • Fixed HTTP header conflict between Content-Length and Transfer-Encoding in res.send - by @YuryShkoda in #4893

    Fixed the behavior of res.send() to prevent conflicts between Content-Length and Transfer-Encoding HTTP headers in responses. The Content-Length header in res.send() is now only added when a Transfer-Encoding header is not present, complying with the HTTP specification that states both headers should not coexist in the same response. ETag generation is unaffected by the presence of a Transfer-Encoding header - by @cuishuang in #7459

🚀 Improvements

  • Allow conditional revalidation for QUERY requests. req.fresh previously only validated freshness for GET and HEAD requests, so QUERY responses never returned 304 despite a matching validator. Since QUERY is a safe, idempotent, and cacheable method that supports conditional requests, it is now included in the freshness check - by @Cherry in #7366 

    // QUERY /reports with If-None-Match: "12345"
app.query('/reports', (req, res) => {
  res.set('ETag', '"12345"');
  res.send(results); // now responds 304 Not Modified
});

  • Improve HTML structure in res.redirect() responses when HTML format is accepted by adding <!DOCTYPE html>, <title>, and <body> tags for better browser compatibility - by @Bernice55231 in #5167

  • When calling app.render with options set to null, the locals object is handled correctly, preventing unexpected errors and making the method behave the same as when options is omitted or an empty object is passed - by AkaHarshit in #6903 

    app.render('index', null, callback); // now works as expected

  • Upgrade content-type to ^2.0.0, bringing a faster parser (~1.5x quicker Content-Type parsing/formatting in res.send()) along with a behavior change: res.send() now keeps any existing parameters when adding the charset and no longer throws on a Content-Type that fails to parse. type-is is upgraded to ^2.1.0 as part of the same change - by @blakeembrey in #7234 

    res.set('Content-Type', 'text/plain; foo=bar').send('hey');
// -> Content-Type: text/plain; foo=bar; charset=utf-8

  • The default error handler now logs the full error object instead of only its stack trace, so nested details such as Error.cause and library-specific properties (e.g. Sequelize's parent/original) are no longer swallowed - by @Nitin-Mohapatra in #6464

  • Upgrade content-disposition to ^2.0.1, which changes the Content-Disposition header emitted by res.download(), res.attachment(), and res.sendFile(): file names that are valid HTTP tokens are no longer wrapped in quotes. This is equivalent per RFC 6266, but applications asserting on the exact header bytes should update their expectations - by @blakeembrey in #7233 

    res.attachment('user.html');
// before -> Content-Disposition: attachment; filename="user.html"
// after  -> Content-Disposition: attachment; filename=user.html

  • Upgrade body-parser to ^2.3.0, which fixes CVE-2026-12590 (GHSA-v422-hmwv-36x6): an invalid limit option value caused request body size enforcement to be silently disabled (fail-open), allowing a denial of service via arbitrarily large payloads. Invalid limit values now throw at parser initialization instead of being ignored - by @Mayvis in #7390

⚡ Performance

  • Avoid duplicate Content-Type header processing in res.send() when sending string responses without an explicit Content-Type header - by @bjohansebas in #6991

What's Changed

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Full Changelog: v5.2.1...v5.3.0

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