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POST /users/v1/login had no throttling, lockout, or backoff, allowing unlimited credential brute-forcing. Adds an in-memory lockout keyed by client IP + attempted username: after 5 failed attempts within a 60s window, further attempts (including with the correct password) get a 429 with Retry-After until the window expires. Successful login clears the counter for that key; unrelated accounts/IPs are unaffected. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
🏆 VAmPI — CTF Patch Score0 / 9 challenges patched
Commit: No points yet — this commit didn't solve any challenges, so there's nothing on the leaderboard for it. Patch a vulnerability and push again! 💪 |
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Vulnerability
POST /users/v1/loginhad no throttling, lockout, or backoff of any kind, so credentials could be brute-forced with unlimited attempts (API4:2019 Lack of Resources & Rate Limiting).Fix
Added an in-memory login lockout in
api_views/users.py, keyed by client IP + the attempted username:429 Too Many Requestswith aRetry-Afterheader until the window expires.No new third-party dependency required.
Testing (local, WSL)
vulnerable=1), seeded via/createdb.name1-> all200with the existing bad-password message.429lockout message, confirming the brute-force is now throttled.name1while still inside the lockout window -> still429, confirming lockout can't be bypassed by eventually guessing right.name2) duringname1's lockout -> succeeded normally (200+ auth token), confirming unrelated accounts aren't affected.name1with the correct password -> succeeded normally (200+ auth token), confirming legitimate login still works once the lockout clears.🤖 Generated with Claude Code