🟡 Medium Security Finding
Scanner: Trivy
Rule: GHSA-67mh-4wv8-2f99
Severity: MEDIUM
File: pnpm-lock.yaml:1
Description
Package: esbuild
Installed Version: 0.18.20
Vulnerability GHSA-67mh-4wv8-2f99
Severity: MEDIUM
Fixed Version: 0.25.0
Link: GHSA-67mh-4wv8-2f99
Remediation Guidance
Vulnerability GHSA-67mh-4wv8-2f99
Severity: MEDIUM
Package: esbuild
Fixed Version: 0.25.0
Link: GHSA-67mh-4wv8-2f99
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.
References
This issue was automatically created by repo-sentinel. Assigned to Copilot for an automated fix attempt.
🟡 Medium Security Finding
Scanner: Trivy
Rule:
GHSA-67mh-4wv8-2f99Severity: MEDIUM
File:
pnpm-lock.yaml:1Description
Package: esbuild
Installed Version: 0.18.20
Vulnerability GHSA-67mh-4wv8-2f99
Severity: MEDIUM
Fixed Version: 0.25.0
Link: GHSA-67mh-4wv8-2f99
Remediation Guidance
Vulnerability GHSA-67mh-4wv8-2f99
Severity: MEDIUM
Package: esbuild
Fixed Version: 0.25.0
Link: GHSA-67mh-4wv8-2f99
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:
http://malicious.example.com).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.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
/index.html: normally you have a script tag here/assets: it's common to have aassetsdirectory when you have JS files and CSS files in a different directory and the directory listing feature tells the attacker the list of files/esbuildSSE 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)))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
npm inpm run watchfetch('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.
References
This issue was automatically created by repo-sentinel. Assigned to Copilot for an automated fix attempt.