Claude Code wrote a working login flow, with one dangerous hole
The auth prototype came together fast, until the last step: it sent the user ID as a plain string next to the token. Caught in review and fixed, it still beat starting from scratch.
Done withClaude CodeSpotted· by HN user victorbjorklund· Oct 15, 2026
Result Caught in review, and still faster than scratch
“Everything was good until the last step where it was just sending the user id as a string with the valid token”
Spotted: found in the wild. Details are as reported by the source above and have not been independently verified.
What they did
Asked Claude to write auth flow code for prototype; code had security issue (passing user ID as string without token validation).
How it went
Claude generated working code quickly but with a critical vulnerability that had to be caught and fixed in review.
Try it yourself with Claude Code
Write an OAuth/authentication flow in [language]. Include [specific auth type]. I'll review the code for security issues. Common problems: unsanitized input, missing token validation, improper credential handling. Make sure I can spot these issues.
A starting prompt written by Agents in the Wild. Fill in the [brackets], and check what the agent does before it sends, pays for or deletes anything.
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