chore(deps): update dependency esbuild to ^0.28.0 [security] by renovate[bot] · Pull Request #234 · OneLiteFeatherNET/feedback-fusion

renovate · 2026-06-12T22:52:50Z

This PR contains the following updates:

Package	Change	Age	Confidence
esbuild	`^0.27.3` → `^0.28.0`

esbuild enables any website to send any requests to the development server and read the response

GHSA-67mh-4wv8-2f99

More information

Details

Summary

esbuild allows any websites to send any request to the development server and read the response due to default CORS settings.

Details

esbuild sets Access-Control-Allow-Origin: * header to all requests, including the SSE connection, which allows any websites to send any request to the development server and read the response.

https://github.com/evanw/esbuild/blob/df815ac27b84f8b34374c9182a93c94718f8a630/pkg/api/serve_other.go#L121
https://github.com/evanw/esbuild/blob/df815ac27b84f8b34374c9182a93c94718f8a630/pkg/api/serve_other.go#L363

Attack scenario:

The attacker serves a malicious web page (http://malicious.example.com).
The user accesses the malicious web page.
The attacker sends a fetch('http://127.0.0.1:8000/main.js') request by JS in that malicious web page. This request is normally blocked by same-origin policy, but that's not the case for the reasons above.
The attacker gets the content of http://127.0.0.1:8000/main.js.

In this scenario, I assumed that the attacker knows the URL of the bundle output file name. But the attacker can also get that information by

Fetching /index.html: normally you have a script tag here
Fetching /assets: it's common to have a assets directory when you have JS files and CSS files in a different directory and the directory listing feature tells the attacker the list of files
Connecting /esbuild SSE endpoint: the SSE endpoint sends the URL path of the changed files when the file is changed (new EventSource('/esbuild').addEventListener('change', e => console.log(e.type, e.data)))
Fetching URLs in the known file: once the attacker knows one file, the attacker can know the URLs imported from that file

The scenario above fetches the compiled content, but if the victim has the source map option enabled, the attacker can also get the non-compiled content by fetching the source map file.

PoC

Download reproduction.zip
Extract it and move to that directory
Run npm i
Run npm run watch
Run fetch('http://127.0.0.1:8000/app.js').then(r => r.text()).then(content => console.log(content)) in a different website's dev tools.

Impact

Users using the serve feature may get the source code stolen by malicious websites.

Severity

CVSS Score: 5.3 / 10 (Medium)
Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

References

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

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

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

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.

`v0.27.7`

Compare Source

Fix lowering of define semantics for TypeScript parameter properties (#4421)

The previous release incorrectly generated class fields for TypeScript parameter properties even when the configured target environment does not support class fields. With this release, the generated class fields will now be correctly lowered in this case:

// Original code
class Foo {
  constructor(public x = 1) {}
  y = 2
}

// Old output (with --loader=ts --target=es2021)
class Foo {
  constructor(x = 1) {
    this.x = x;
    __publicField(this, "y", 2);
  }
  x;
}

// New output (with --loader=ts --target=es2021)
class Foo {
  constructor(x = 1) {
    __publicField(this, "x", x);
    __publicField(this, "y", 2);
  }
}

`v0.27.5`

Compare Source

Fix for an async generator edge case (#4401, #4417)

Support for transforming async generators into the equivalent state machine was added in version 0.19.0. However, the generated state machine didn't work correctly when polling async generators concurrently, such as in the following code:
```
async function* inner() { yield 1; yield 2 }
async function* outer() { yield* inner() }
let gen = outer()
for await (let x of [gen.next(), gen.next()]) console.log(x)
```
Previously esbuild's output of the above code behaved incorrectly when async generators were transformed (such as with --supported:async-generator=false). The transformation should be fixed starting with this release.

This fix was contributed by @2767mr.
Fix a regression when metafile is enabled (#4420, #4418)

This release fixes a regression introduced by the previous release. When metafile: true was enabled in esbuild's JavaScript API, builds with build errors were incorrectly throwing an error about an empty JSON string instead of an object containing the build errors.
Use define semantics for TypeScript parameter properties (#4421)

Parameter properties are a TypeScript-specific code generation feature that converts constructor parameters into class fields when they are prefixed by certain keywords. When "useDefineForClassFields": true is present in tsconfig.json, the TypeScript compiler automatically generates class field declarations for parameter properties. Previously esbuild didn't do this, but esbuild will now do this starting with this release:
```
// Original code
class Foo {
  constructor(public x: number) {}
}

// Old output (with --loader=ts)
class Foo {
  constructor(x) {
    this.x = x;
  }
}

// New output (with --loader=ts)
class Foo {
  constructor(x) {
    this.x = x;
  }
  x;
}
```
Allow es2025 as a target in tsconfig.json (#4432)

TypeScript recently added es2025 as a compilation target, so esbuild now supports this in the target field of tsconfig.json files, such as in the following configuration file:
```
{
  "compilerOptions": {
    "target": "ES2025"
  }
}
```
As a reminder, the only thing that esbuild uses this field for is determining whether or not to use legacy TypeScript behavior for class fields. You can read more in the documentation.

`v0.27.4`

Compare Source

Fix a regression with CSS media queries (#4395, #4405, #4406)

Version 0.25.11 of esbuild introduced support for parsing media queries. This unintentionally introduced a regression with printing media queries that use the <media-type> and <media-condition-without-or> grammar. Specifically, esbuild was failing to wrap an or clause with parentheses when inside <media-condition-without-or>. This release fixes the regression.

Here is an example:
```
/* Original code */
@&#8203;media only screen and ((min-width: 10px) or (min-height: 10px)) {
  a { color: red }
}

/* Old output (incorrect) */
@&#8203;media only screen and (min-width: 10px) or (min-height: 10px) {
  a {
    color: red;
  }
}

/* New output (correct) */
@&#8203;media only screen and ((min-width: 10px) or (min-height: 10px)) {
  a {
    color: red;
  }
}
```
Fix an edge case with the inject feature (#4407)

This release fixes an edge case where esbuild's inject feature could not be used with arbitrary module namespace names exported using an export {} from statement with bundling disabled and a target environment where arbitrary module namespace names is unsupported.

With the fix, the following inject file:
```
import jquery from 'jquery';
export { jquery as 'window.jQuery' };
```
Can now always be rewritten as this without esbuild sometimes incorrectly generating an error:
```
export { default as 'window.jQuery' } from 'jquery';
```
Attempt to improve API handling of huge metafiles (#4329, #4415)

This release contains a few changes that attempt to improve the behavior of esbuild's JavaScript API with huge metafiles (esbuild's name for the build metadata, formatted as a JSON object). The JavaScript API is designed to return the metafile JSON as a JavaScript object in memory, which makes it easy to access from within a JavaScript-based plugin. Multiple people have encountered issues where this API breaks down with a pathologically-large metafile.

The primary issue is that V8 has an implementation-specific maximum string length, so using the JSON.parse API with large enough strings is impossible. This release will now attempt to use a fallback JavaScript-based JSON parser that operates directly on the UTF8-encoded JSON bytes instead of using JSON.parse when the JSON metafile is too big to fit in a JavaScript string. The new fallback path has not yet been heavily-tested. The metafile will also now be generated with whitespace removed if the bundle is significantly large, which will reduce the size of the metafile JSON slightly.

However, hitting this case is potentially a sign that something else is wrong. Ideally you wouldn't be building something so enormous that the build metadata can't even fit inside a JavaScript string. You may want to consider optimizing your project, or breaking up your project into multiple parts that are built independently. Another option could potentially be to use esbuild's command-line API instead of its JavaScript API, which is more efficient (although of course then you can't use JavaScript plugins, so it may not be an option).

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codecov · 2026-06-12T23:04:06Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.74%. Comparing base (d2bfc2a) to head (5d62649).

@@           Coverage Diff           @@
##             main     #234   +/-   ##
=======================================
  Coverage   80.74%   80.74%           
=======================================
  Files          26       26           
  Lines        2462     2462           
=======================================
  Hits         1988     1988           
  Misses        474      474

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

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

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chore(deps): update dependency esbuild to ^0.28.0 [security]#234

chore(deps): update dependency esbuild to ^0.28.0 [security]#234
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esbuild enables any website to send any requests to the development server and read the response

Details

Summary

Details

PoC

Impact

Severity

References

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

Details

Summary

Details

Vulnerable Code

Steps to reproduce

Impact

Severity

References

Release Notes

v0.28.1

v0.28.0

v0.27.7

v0.27.5

v0.27.4

Configuration

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renovate Bot commented Jun 12, 2026 •

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`v0.28.1`

`v0.28.0`

`v0.27.7`

`v0.27.5`

`v0.27.4`