Managing web security effectively is critical, especially for WordPress site owners who rely on both server-level and application-level protections. However, sometimes security measures can work against each other – as was the case when Cloudflare’s Firewall Rules and a popular WordPress Security Plugin began to double-block legitimate requests, resulting in intermittent and frustrating 403 Forbidden errors. Here’s an in-depth look at how these overlapping policies caused conflicts and what steps were taken to resolve the issue.
TLDR: When Cloudflare Firewall Rules and WordPress security plugins like Wordfence or iThemes Security both act on the same types of threats, it can lead to redundant or conflicting actions. This “double blocking” was the root cause of sporadic 403 errors on various parts of the site. By analyzing logs, disabling overlapping features, and aligning policy intent between layers, these random errors were eliminated, providing both security and reliability.
Understanding the Stack: Cloudflare and WordPress Security Plugins
Cloudflare operates at the DNS and CDN level, offering DDoS mitigation, firewall capabilities, and traffic optimization. On the other hand, WordPress security plugins work at the application level, monitoring user behavior, file changes, and login attempts, among others. While both systems are meant to protect the site, their simultaneous use can become problematic when their rules begin to overlap.
The issue arises when both Cloudflare and a WordPress plugin block or throttle a visitor for the same behavior — such as an unusual user-agent or repeated login attempts. When this happens, the visitor often sees a cryptic 403 Forbidden error but with little detail as to which layer is responsible.
Symptoms of a Double Blocking Scenario
Identifying the root of random 403 errors requires careful observation. Here are common symptoms seen during this conflict:
- Only some users experience 403 errors randomly during routine actions (e.g., commenting or submitting a form).
- The site owner is unable to reproduce the issue consistently.
- Cloudflare analytics show blocks or JS Challenge passes, while WordPress logs show blocked IPs or login failures.
- WordPress behaves normally when accessed directly without passing through Cloudflare (by pointing local DNS away from Cloudflare).
Digging into the Logs: Where Is the Conflict?
One of the first techniques to diagnose double blocking is to correlate the timestamp of errors with logs from both Cloudflare and the WordPress security plugin. Cloudflare’s Firewall Logs (available through the Dashboard or via API) will show if a user was challenged or blocked and for what reason.
Similarly, the WordPress plugin (like Wordfence) provides log entries showing blocked actions or suspicious behavior. In our case, a pattern showed users being partially blocked by Cloudflare and then fully blocked by the plugin due to temporarily flagged behavior — creating a situation where the response code didn’t clearly indicate which layer issued the denial.
Conflicting Policies That Triggered Double Blocking
After weeks of analysis, several specific overlapping configurations were identified:
- Rate Limiting: Cloudflare and the plugin both had rate limiting rules – one on the number of page hits per minute, the other on failed login attempts. A triggered rule would make the next layer treat the user as hostile.
- IP Blocking: Both tools maintained a blocklist, and some IPs were blocked in one but not the other, causing inconsistent results across requests.
- User-Agent Filtering: Cloudflare blocked certain bots, while the plugin blocked known scrapers – again, overlapping patterns created unexpected denials.
Aligning Firewall Rules and Security Plugin Policies
Solving the issue required aligning both systems so they complement each other rather than compete. Here are the steps taken:
1. Audit Security Goals
First, the purpose of each security measure was reviewed. Cloudflare was best suited for:
- Protecting against DDoS attacks and bot abuse at the edge.
- Serving cached content from global locations.
- Blocking known malicious ASNs and geographies.
In contrast, the WordPress plugin focused more on:
- Preventing brute force login attempts.
- Monitoring file integrity inside WordPress.
- Blocking suspicious behavior like parameter tampering or injection attempts.
2. Remove Redundant IP Blocking
The second step was to centralize IP blocking. Cloudflare was chosen to manage this at the edge, and the firewall within the plugin was told to disable real-time IP blacklisting — thus preventing multiple places from blocking the same request for the same behavior.
3. Rate Limiting Adjustment
Custom rules were created in Cloudflare to reduce aggressiveness in rate limiting, especially for paths like /wp-login.php and /xmlrpc.php, allowing the plugin to handle abuse on those endpoints with finer granularity.
4. Exceptions Based on Headers
A rule was set in the WordPress plugin to ignore specific custom headers added only by Cloudflare (like CF-Connecting-IP). This helped distinguish between true users and misidentified bots.
5. Disable Certain Plugin Firewall Features
Where Cloudflare already filtered similar threats – such as SQL injection patterns or known bad bots – those plugin features were disabled to avoid duplication.
Outcome: Seamless Yet Strong Protection
The result of aligning these layers was a smoother user experience and fewer false positives. No more unexplained 403 errors. Performance also saw a minor improvement due to reduced overhead in handling redundant checks.
The key lesson: Having multiple layers of security doesn’t mean deploying multiple overlapping versions of the same tool. Each layer should play a distinct role in the security strategy.
Best Practices to Prevent Double Blocking
To avoid experiencing similar issues in the future, consider the following:
- Only one layer should actively manage IP blocking or bot detection.
- Regularly monitor logs from both Cloudflare and WordPress plugins together for correlation.
- Document every active rule or setting change in a shared config log or admin note.
- Use Cloudflare’s Page Rules or Firewall Rules to pass or bypass IPs on specific paths when needed.
FAQ
- Q: Why was I seeing random 403 errors if my site was secure?
- A 403 error means access was denied — but in this case, it was often due to conflicting rules, not actual threats. Both Cloudflare and the WordPress plugin tried to act on the same user behavior, causing the user to be blocked twice.
- Q: Which tool should handle IP blocking, Cloudflare or the plugin?
- Cloudflare is better suited for IP blocking because it acts earlier in the request chain and reduces server load. The WordPress plugin should focus on handling app-specific attacks.
- Q: Can I disable firewall features in my plugin without risking my site?
- Yes, especially if Cloudflare already provides similar protections — just ensure that the remaining plugin features are still covering behaviors at the application level.
- Q: What logs should I check to diagnose 403 errors?
- Check Cloudflare’s Firewall Logs and your WordPress plugin’s security logs. Cross-reference timestamps and IPs to find where the block is occurring.
- Q: What’s the best practice for handling login protection?
- Let the plugin handle login-specific behaviors like lockouts or CAPTCHA, while using Cloudflare to throttle login attempts or apply basic bot detection at the edge.