Every MINOR line inside 1.x receives security patches for the life of the 1.x series. Non-security bug fixes land on the latest MINOR only; back-ports on request (open an issue).

If you believe you've found a security issue in captchakit, please do not open a public GitHub issue. Instead, email pypi@kerempy.com.tr with:

• a short description of the issue,
• steps to reproduce (or a proof-of-concept), and
• the affected version(s).

You'll get an acknowledgement within 72 hours. If the issue is confirmed I'll work with you on a fix and a coordinated disclosure timeline (typically 30 days from confirmation).

captchakit is a lightweight human-check intended to raise the cost of casual / scripted spam in use cases such as:

• Telegram / Discord join-verification
• low-value FastAPI sign-up or contact forms
• internal tools

It is not a defence against a determined attacker using modern OCR or a human-solver farm. For high-value surfaces (login, payment, password reset) use a purpose-built service such as hCaptcha, Cloudflare Turnstile, or reCAPTCHA Enterprise, ideally in addition to captchakit.

• Constant-time answer comparison (hmac.compare_digest) — timing side channels on the verification path are mitigated.
• Cryptographically secure solution generation (secrets.choice, secrets.randbelow) — solutions are not predictable from prior outputs.
• TTL + attempt limits enforced by CaptchaManager — a stolen challenge id has a bounded lifetime and a bounded number of guesses.
• No solution logging by default — solutions live only in the selected storage backend and are evicted on success, failure-with-attempts-exhausted, or TTL expiry.

• Automated OCR — the built-in ImageRenderer is not OCR-resistant. It's a visual check, not a CV-hardened one.
• Replay of the image to a solver farm — any third-party solver that can read the prompt can answer correctly. Combine with rate limiting.
• Shared state across processes in MemoryStorage — use RedisStorage or PostgresStorage for multi-worker deployments.
• Challenge-id enumeration — ids are UUID4 (122 bits of randomness) so guessing is infeasible, but if your application leaks ids (e.g. in logs or URLs) an attacker can try to solve them directly.

Core runtime dependencies are deliberately minimal: Pillow only. Every framework adapter and storage backend lives behind an optional extra, so you can audit exactly what your deployment pulls in.