CORS origin parsing bug

A bug bounty hunter reported that our CORS configuration allows any domain that ends with our domain name, or has a different character instead of the dot.

Initial failing signalhidden.test.mjs fails on malicious domainsExpected behavior: A malicious lookalike origin is rejected. · actual behavior: The malicious lookalike origin is accepted.

Progress

1Reproduce the bugRun checks

2Edit the fixOpen

3Pass checksOpen

4Submit fixOpen

Reproduction Steps

Run npm test.
Compare allowed first-party origins with suffix lookalikes.
Trace how the configured domain becomes an origin matcher.
Keep legitimate origins working while rejecting lookalikes.

Focus Mode

Start

src/index.js

Likely area

src/index.js

Challenge Coach

Hints reveal broad direction first, then narrow toward the suspect path without showing hidden tests or exact solution code.

TopicSecurity

DifficultyMedium

Est. time15 min

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Evidence Map

Failing signal loaded from challenge API
Workspace files loaded from workspace API
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workspace

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