Permissions Policy (Feature Policy) Header Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching permissions policy (feature policy) header, 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

# Permissions Policy (Feature Policy) Header
# ReDoS-safe | RegexVault — Security > Security Headers

import re

permissions_policy_feature_policy_header_pattern = re.compile(r'^(camera|microphone|geolocation|payment|usb|fullscreen|display-capture|gyroscope|accelerometer|magnetometer|ambient-light-sensor|autoplay|encrypted-media|midi|picture-in-picture|speaker-selection|sync-xhr|vibrate|web-share|clipboard-read|clipboard-write|interest-cohort|screen-wake-lock|xr-spatial-tracking)=\((\*|self(?:\s+"https?://[^"]+")*|)\)$')

def validate_permissions_policy_feature_policy_header(value: str) -> bool:
    return bool(permissions_policy_feature_policy_header_pattern.fullmatch(value))

# Example
print(validate_permissions_policy_feature_policy_header("camera=()"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Security > Security Headers 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

Permissions Policy (formerly Feature Policy) controls which browser features are available to a page. camera=(), microphone=(), geolocation=() disables the feature completely. () = nobody, (self) = same origin only, (*) = all origins. Prevents third-party scripts from activating features.