How nullcipher recognises it
ghp_, gho_, ghu_, ghs_ or ghr_ followed by 36 or more letters and digits, or a fine-grained github_pat_ token.
This is the rule text of the “GitHub token” detector in the masking engine, copied from the engine when this page was built. Detectors run in a fixed order and, where two overlap, the earlier one wins.
Example (fake)
ghp_EXAMPLE0000000000000000000000000000abcd
nullcipher replaces it with [GITHUB_TOKEN_1]. The part after ghp_ is the word EXAMPLE padded with zeros. GitHub never issued it.
Why it matters in an AI chat
GitHub puts the token's kind in its prefix: ghp_ is a personal access token (classic), github_pat_ a fine-grained personal access token, gho_ an OAuth access token, ghu_ a user access token for a GitHub App, ghs_ an installation access token for a GitHub App and ghr_ a refresh token for a GitHub App.
A personal access token acts as you, with whatever scopes it was given. A classic token with the repo scope can read and push to every private repository you can.
GitHub automatically revokes a token that is pushed to a public repository or a public gist. An AI chat is neither, so nothing revokes a pasted token for you.
If it already leaked
- Personal access token: profile picture → Settings → Developer settings → Personal access tokens → Fine-grained tokens or Tokens (classic), then Delete next to the token. [2]
- Token that belongs to a GitHub App or OAuth app: revoking your authorization of that app in your account settings revokes every token associated with it. [3]
- GitHub's advice for a leaked secret is to rotate the credential immediately; it notes that removing a secret from Git history is time-intensive and often unnecessary once the credential is revoked. The same logic applies to a chat: revoking beats deleting. [4]
- Create a new token with only the scopes and repositories it needs, and set an expiry date on it.
Sources
- About authentication to GitHub — GitHub's token formats — checked 2026-09-23.
- Managing your personal access tokens — GitHub Docs — checked 2026-09-23.
- Token expiration and revocation — GitHub Docs — checked 2026-09-23.
- About secret scanning — GitHub Docs — checked 2026-09-23.
Open the full masking tool to mask a whole log, .env file or e-mail — every type at once — and restore the values in the AI's answer. Or see all 16 secret types and how to delete a chat you already sent.