Cookie Name=Value Pair Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching cookie name=value pair, ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. 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

# Cookie Name=Value Pair
# ReDoS-safe | RegexVault — Web & Network > HTTP

import re

cookie_namevalue_pair_pattern = re.compile(r'^([!#-'*-+\-.0-9A-Z^-z|~]+)=([\x21\x23-\x2B\x2D-\x3A\x3C-\x5B\x5D-\x7E]*)$')

def validate_cookie_namevalue_pair(value: str) -> bool:
    return bool(cookie_namevalue_pair_pattern.fullmatch(value))

# Example
print(validate_cookie_namevalue_pair("session=abc123"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > HTTP 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

Cookie names cannot contain separators, whitespace, or control characters. Values cannot contain whitespace, comma, semicolon, or backslash. Many cookies in practice use base64 — the character set is compatible.