Cache Poisoning in Strapi with Cockroachdb

Cache poisoning occurs when an attacker manipulates cached data so that subsequent requests receive malicious or incorrect responses. In a Strapi application backed by Cockroachdb, this risk arises from a mismatch between caching behavior and the database’s strong consistency guarantees when misconfigured.

Strapi, by default, may cache database query results at the application layer or via an external cache to reduce load on Cockroachdb. Cockroachdb provides serializable isolation and strongly consistent reads, but if Strapi caches responses that include user-specific or role-specific data without incorporating request context (such as user ID or tenant ID) into the cache key, one user’s cached response can be served to another user. This is a BOLA/IDOR condition introduced by the cache layer.

For example, if Strapi caches the JSON response of /api/articles based only on the endpoint path and query parameters visible to unauthenticated or low-privilege requests, and that cache entry contains an author ID or sensitive field, an attacker can craft requests that reuse the poisoned cache key. Because Cockroachdb commits are consistent and linearizable, the cached data may remain valid for a long time, extending the window of exposure. The risk is compounded when the cache is shared across instances or when cache invalidation on update/delete is not tightly coupled to Cockroachdb transaction commit events.

Another vector involves query parameter pollution: Strapi may build cache keys from a subset of parameters while ignoring others that change authorization context (e.g., user_id, role). An attacker who can inject additional parameters or manipulate headers might cause the application to retrieve a cached response intended for a higher-privilege context. Because Cockroachdb enforces strict consistency, the authoritative data is correct, but the cache delivers an outdated or unauthorized snapshot.

LLM/AI Security checks in middleBrick can surface these issues by detecting unauthenticated endpoints that return user-specific data and by correlating spec definitions with runtime behavior. When scanning a Strapi API backed by Cockroachdb, middleBrick flags insecure caching as a finding and maps it to relevant portions of the OWASP API Top 10 and compliance frameworks.

Remediation focuses on ensuring cache keys incorporate authorization context and that cache invalidation aligns with Cockroachdb transactions. Avoid caching responses that contain user-specific or role-specific data unless the cache key includes a tenant or user identifier.

1. Include user or tenant identifiers in cache keys. If you use a custom caching layer, build keys that reflect the request context. For example, when fetching articles, include the user ID or role in the key:

// Example cache key builder in Strapi (Node.js)
function getCacheKey(ctx) {
  const { user } = ctx.state; // authenticated user from Strapi auth
  const { publicationId, role } = ctx.query;
  return `articles:${publicationId}:${role}:${user ? user.id : 'public'}`;
}

2. Use Cockroachdb transaction hooks to invalidate cache entries. Strapi does not directly manage Cockroachdb transactions, but you can hook into lifecycle events to clear or update cache entries when data changes. In your model service, after a successful update, delete or refresh the affected cache entries:

// Strapi service hook after-update (e.g., src/api/article/services/article.js)
module.exports = {
  async afterUpdate(result, params, context) {
    const cacheKeysToInvalidate = [
      `articles:${params.id}`,
      `articles:list:user:${context.state.user ? context.state.user.id : 'public'}`
    ];
    for (const key of cacheKeysToInvalidate) {
      await strapi.cache.del(key);
    }
    return result;
  }
};

3. Avoid caching responses that contain PII or authorization-sensitive fields. Configure Strapi’s responses and cache rules to exclude sensitive attributes for non-admin roles. In your controller, conditionally strip fields before caching:

// Strapi controller (src/api/article/controllers/article.js)
async find(ctx) {
  const entities = await strapi.entityService.findMany('api::article.article', {
    filters: ctx.request.query.filters,
    pagination: ctx.request.query.pagination,
    populate: ['author']
  });

  const publicView = !ctx.state.user;
  const data = entities.map(entity => {
    if (publicView) {
      const { author, ...safe } = entity;
      return safe;
    }
    return entity;
  });

  // If using an external cache, store the transformed data with a context-aware key
  const cacheKey = getCacheKey(ctx);
  await strapi.cache.set(cacheKey, data, { ttl: 60 });

  return data;
}

4. Align cache TTL with Cockroachdb’s write frequency. For data that changes often, use shorter TTLs to reduce the window of inconsistency. For read-heavy, relatively static data, longer TTLs are acceptable but must still incorporate user context in the key.

5. Validate and sanitize all inputs that influence cache keys. Ensure query parameters that affect authorization (such as role or user_id) cannot be overridden via header smuggling or parameter pollution. MiddleBrick’s input validation checks can help detect unsafe consumption patterns.

By combining context-aware cache keys, precise invalidation tied to Cockroachdb writes, and careful output filtering, you mitigate cache poisoning while preserving performance. middleBrick’s continuous monitoring (Pro plan) can alert you if new endpoints introduce inconsistent caching behavior and map findings to compliance requirements.