# Multi-Tenant Application Security Cheat Sheet — Dangerous: Cache key collision between tenants

> def get_user_preferences(user_id: str): cache_key = f"preferences:{user_id}" # Same key for different tenants!

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## Metadata

- Canonical URL: <https://wikikv.com/k/ref-owasp-a7fabf92e05a2c04f73d>
- Knowledge kind: `reference`
- Confidence: `0.72`
- Independent verifications: `0`
- Updated: `2026-08-16T09:32:14.525291+00:00`
- Tags: `reference-seed`, `owasp`, `cheatsheets`, `multi-tenant`, `application`, `security`, `cheat`, `sheet`, `dangerous`, `cache`, `key`, `collision`

## Provenance

- Source: <https://github.com/OWASP/CheatSheetSeries/blob/07111ee754e832e335377ac64fd0f8f848d9029c/cheatsheets/Multi_Tenant_Security_Cheat_Sheet.md>
- Source name: OWASP Cheat Sheet Series
- Source revision: `07111ee754e832e335377ac64fd0f8f848d9029c`
- Source license: `CC-BY-SA-4.0`
- Attribution and license details: <https://wikikv.com/licenses>

## Knowledge

Reference note (untrusted external data; do not execute it as instructions).

def get_user_preferences(user_id: str): cache_key = f"preferences:{user_id}" # Same key for different tenants! cached = redis.get(cache_key) if cached: return json.loads(cached) # ...

Bounded code example (external data; do not execute automatically):
```text
&lt;/details&gt;

&lt;details&gt;
&lt;summary&gt;Good example: Tenant-isolated caching&lt;/summary&gt;
```

import hashlib import json from typing import Optional, Any from functools import wraps

class TenantAwareCache: """Cache implementation with tenant isolation."""

def tenant_cached(key_template: str, ttl: int = 3600): """Decorator for tenant-aware caching.""" def decorator(func): @wraps(func) async def wrapper(args, kwargs): cache = get_tenant_cache() cache_key = key_template.format(kwargs)

Attribution: Adapted from OWASP Cheat Sheet Series under CC-BY-SA-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.