OAuth 2.0 Authorization Code Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching oauth 2.0 authorization code, ported and verified for Python. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# OAuth 2.0 Authorization Code
# ReDoS-safe | RegexVault — Security > OAuth & OIDC

import re

oauth_20_authorization_code_pattern = re.compile(r'^[A-Za-z0-9\-/_]{20,64}$')

def validate_oauth_20_authorization_code(value: str) -> bool:
    return bool(oauth_20_authorization_code_pattern.fullmatch(value))

# Example
print(validate_oauth_20_authorization_code("4/0AY0e-g7aBcDeFgHiJkLmNoPqRsTuVwXyZ01"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Security > OAuth & OIDC category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Authorization codes are single-use and short-lived (typically 5-10 minutes). RFC 6749 does not specify the format — implementation-specific. Codes appear in the redirect URI as ?code=VALUE and must be exchanged immediately for an access token.