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The "X-Forwarded-Host" header may contain multiple values

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
48/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
express, javascript
Domain
backend

Research direction

Start by locating the Express middleware code that reads the X-Forwarded-Host header. Reproduce the case with a comma-separated header containing multiple values, then verify that the resulting behavior uses the first value as requested. No test file or implementation path is named in the issue.

Written by the indexing model from the issue text.

Description

The current implementation doesn't take into account the X-Forwarded-Host header may contain multiple values.
From the Apache mod_proxy docs:

Be careful when using these headers on the origin server, since they will contain more than one (comma-separated) value if the original request already contained one of these headers.

Probably in such case you should take the first value from the list.

Dominant language
JavaScript
Stars
921
Forks
185
No merged PRs in 30d

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

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