chore(deps): update dependency esbuild to ^0.28.0 [security]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
esbuild	^0.27.0 → ^0.28.0

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esbuild allows arbitrary file read when running the development server on Windows

GHSA-g7r4-m6w7-qqqr

More information

Details

Summary

The development server contains a path traversal vulnerability on Windows when serving files from servedir.

Due to the use of path.Clean() (which only normalizes forward-slash / separators) instead of a Windows-aware path normalization function, it is possible to craft requests using backslashes (\) that bypass the intended directory containment logic. An attacker can escape the configured servedir root and access arbitrary files on the filesystem.
This issue affects Windows environments only.

Details

The request path is sanitized using:

// https://github.com/evanw/esbuild/blob/v0.27.3/pkg/api/serve_other.go#L165
queryPath := path.Clean(req.URL.Path)[1:]

However:

• path.Clean() is POSIX-style and only understands / (docs: https://pkg.go.dev/path#Clean)
• On Windows, \ is a valid path separator
• path.Clean() does not treat \ as a separator

Later, the server constructs the absolute path:

// https://github.com/evanw/esbuild/blob/v0.27.3/pkg/api/serve_other.go#L221
absPath := h.fs.Join(h.servedir, queryPath)

If queryPath contains sequences such as:

..\..\..\..\..\..\..\Windows\system.ini

path.Clean() will not normalize them, but the Windows filesystem will interpret \ as directory separators when resolving absPath.
Because the implementation does not verify that the final resolved path remains within servedir, it allows directory traversal outside the intended root directory.

Vulnerable Code

// https://github.com/evanw/esbuild/blob/v0.27.3/pkg/api/serve_other.go#L165
	queryPath := path.Clean(req.URL.Path)[1:]
	....
	// Check for a file in the "servedir" directory
	if h.servedir != "" && kind != fs.FileEntry {
		absPath := h.fs.Join(h.servedir, queryPath)
		if absDir := h.fs.Dir(absPath); absDir != absPath {
			if entries, err, _ := h.fs.ReadDirectory(absDir); err == nil {
				if entry, _ := entries.Get(h.fs.Base(absPath)); entry != nil && entry.Kind(h.fs) == fs.FileEntry {
	....				

Steps to reproduce

npm install --save-exact --save-dev esbuild

echo "console.log(1)" > app.js

.\node_modules\.bin\esbuild --version
0.27.3

.\node_modules\.bin\esbuild app.js --bundle --outdir=www --servedir=www --watch

curl -i --path-as-is "http://localhost:8000/..\..\..\..\..\..\..\Windows\system.ini"
<content of Windows\system.ini>

Impact

• Arbitrary file read on Windows
• Exposure of sensitive files

Severity

• CVSS Score: 2.5 / 10 (Low)
• Vector String: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

References

• https://github.com/evanw/esbuild/security/advisories/GHSA-g7r4-m6w7-qqqr
• https://github.com/evanw/esbuild/releases/tag/v0.28.1
• https://github.com/advisories/GHSA-g7r4-m6w7-qqqr

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

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Release Notes

evanw/esbuild (esbuild)

v0.28.1

Compare Source

• Disallow \ in local development server HTTP requests (GHSA-g7r4-m6w7-qqqr)

  This release fixes a security issue where HTTP requests to esbuild's local development server could traverse outside of the serve directory on Windows using a \ backslash character. It happened due to the use of Go's path.Clean() function, which only handles Unix-style / characters. HTTP requests with paths containing \ are no longer allowed.

  Thanks to @​dellalibera for reporting this issue.

• Add integrity checks to the Deno API (GHSA-gv7w-rqvm-qjhr)

  The previous release of esbuild added integrity checks to esbuild's npm install script. This release also adds integrity checks to esbuild's Deno install script. Now esbuild's Deno API will also fail with an error if the downloaded esbuild binary contains something other than the expected content.

  Note that esbuild's Deno API installs from registry.npmjs.org by default, but allows the NPM_CONFIG_REGISTRY environment variable to override this with a custom package registry. This change means that the esbuild executable served by NPM_CONFIG_REGISTRY must now match the expected content.

  Thanks to @​sondt99 for reporting this issue.

• Avoid inlining using and await using declarations (#​4482)

  Previously esbuild's minifier sometimes incorrectly inlined using and await using declarations into subsequent uses of that declaration, which then fails to dispose of the resource correctly. This bug happened because inlining was done for let and const declarations by avoiding doing it for var declarations, which no longer worked when more declaration types were added. Here's an example:

  // Original code
  {
    using x = new Resource()
    x.activate()
  }
  
  // Old output (with --minify)
  new Resource().activate();
  
  // New output (with --minify)
  {using e=new Resource;e.activate()}

• Fix module evaluation when an error is thrown (#​4461, #​4467)

  If an error is thrown during module evaluation, esbuild previously didn't preserve the state of the module for subsequent module references. This was observable if import() or require() is used to import a module multiple times. The thrown error is supposed to be thrown by every call to import() or require(), not just the first. With this release, esbuild will now throw the same error every time you call import() or require() on a module that throws during its evaluation.

• Fix some edge cases around the new operator (#​4477)

  Previously esbuild incorrectly printed certain edge cases involving complex expressions inside the target of a new expression (specifically an optional chain and/or a tagged template literal). The generated code for the new target was not correctly wrapped with parentheses, and either contained a syntax error or had different semantics. These edge cases have been fixed so that they now correctly wrap the new target in parentheses. Here is an example of some affected code:

  // Original code
  new (foo()`bar`)()
  new (foo()?.bar)()
  
  // Old output
  new foo()`bar`();
  new (foo())?.bar();
  
  // New output
  new (foo())`bar`();
  new (foo()?.bar)();

• Fix renaming of nested var declarations (#​4471)

  This release fixes a bug where var declarations in nested scopes that are hoisted up to module scope were not correctly being renamed during bundling. That could previously lead to name collisions when minification was disabled, which could potentially cause a behavior change. The bug has been fixed so that these hoisted declarations are now considered to be module-level symbols during the name collision avoidance pass.

• Emit var instead of const for certain TypeScript-only constructs for ES5 (#​4448)

  While esbuild doesn't generally support converting const to var for ES5 due to nested scoping rules (which is currently a build-time error), esbuild previously incorrectly converted TypeScript-only import assignment constructs into a const declaration even when targeting ES5. With this release, esbuild will now use var for this case instead:

  // Original code
  import x = require('y')
  
  // Old output (with --target=es5)
  const x = require("y");
  
  // New output (with --target=es5)
  var x = require("y");

v0.28.0

Compare Source

• Add support for with { type: 'text' } imports (#​4435)

  The import text proposal has reached stage 3 in the TC39 process, which means that it's recommended for implementation. It has also already been implemented by Deno and Bun. So with this release, esbuild also adds support for it. This behaves exactly the same as esbuild's existing text loader. Here's an example:

  import string from './example.txt' with { type: 'text' }
  console.log(string)

• Add integrity checks to fallback download path (#​4343)

  Installing esbuild via npm is somewhat complicated with several different edge cases (see esbuild's documentation for details). If the regular installation of esbuild's platform-specific package fails, esbuild's install script attempts to download the platform-specific package itself (first with the npm command, and then with a HTTP request to registry.npmjs.org as a last resort).

  This last resort path previously didn't have any integrity checks. With this release, esbuild will now verify that the hash of the downloaded binary matches the expected hash for the current release. This means the hashes for all of esbuild's platform-specific binary packages will now be embedded in the top-level esbuild package. Hopefully this should work without any problems. But just in case, this change is being done as a breaking change release.

• Update the Go compiler from 1.25.7 to 1.26.1

  This upgrade should not affect anything. However, there have been some significant internal changes to the Go compiler, so esbuild could potentially behave differently in certain edge cases:

  • It now uses the new garbage collector that comes with Go 1.26.
  • The Go compiler is now more aggressive with allocating memory on the stack.
  • The executable format that the Go linker uses has undergone several changes.
  • The WebAssembly build now unconditionally makes use of the sign extension and non-trapping floating-point to integer conversion instructions.

  You can read the Go 1.26 release notes for more information.

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