New Year, New Shell: Starting 2026 with a P1 RCE

They say the best way to predict the future is to create it. For me, 2026 started with a blast. After two years underground away from the leaderboards, focusing on deep technical research and architectural security I decided it was time to step back into the arena. I didn't want to just "check in"; I wanted to make a statement.

I set my sights on a hardened, high-profile target within a private bug bounty program. I wasn't hunting for low-hanging fruit. I was looking for a total system compromise.

The Result?

A Critical (P1) Unauthenticated Remote Code Execution (RCE)/ complete site takeover .

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Technical Vulnerability Overview

Metric: Details

  • Vulnerability Class: Remote Code Execution (RCE) / Site Takeover
  • CWE ID: CWE-306 (Missing Authentication for Critical Function)
  • Severity: Critical (P1)
  • CVSS v3.1 Score: 9.8 (Critical)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • Affected Component: WordPress Installation Wizard (setup-config.php)
  • Root Cause: Unconfigured staging environment exposed to public internet

1. The Strategy: Precision Reconnaissance

Most researchers rush. They make enough noise to wake up every SOC on the planet. I moved slowly.

While mapping the infrastructure, I discovered a staging environment that seemed quiet. But the server configuration was whispering secrets. I immediately noticed that Directory Listing was enabled. This was my first "way in." By browsing through the /wp-content/ directories, I wasn't just seeing files; I was mapping the site's defensive posture and internal structure.

2. Finding the "Ghost" in the Upgrade Folder

While digging through the /wp-content/upgrade/ directory, I found something that should never be left behind: a leftover update package from a WordPress 6.8.3 migration. Inside this temporary folder sat a "nested" WordPress installation that was completely unconfigured.

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3. The Critical Chain: From Setup to Shell

This is where the magic happens. By navigating to the exposed setup-config.php within that upgrade path, I was greeted by the WordPress Installation Wizard.

The Kill-Chain:

ATTACKER (Me) │ ├── [1] RECONNAISSANCE │ └── Discovered Directory Listing Enabled │ └── Found path: /wp-content/upgrade/ │ ├── [2] ENUMERATION │ └── Located hidden installation wizard │ └── Endpoint: /wp-admin/setup-config.php │ ├── [3] EXPLOITATION (The Critical Moment) │ └── Application asks for Database Credentials │ └── Attacker provides MALICIOUS EXTERNAL DB details │ ├── [4] TAKEOVER │ └── WordPress installs connected to Attacker's DB │ └── Attacker creates NEW ADMIN account │ └── [5] IMPACT (RCE) └── Admin Login -> Theme Editor -> Shell Upload └── FULL SERVER COMPROMISE

  • The Entry Point: The wizard requested database credentials.
  • The Takeover: As an attacker, I could have provided my own remote database credentials. The server would have connected to my database, allowing me to complete the installation and become the Super Administrator.
  • The RCE: With Admin access, the path to a shell is trivial. Using the theme editor to inject a PHP backdoor gives full command execution over the underlying server.

4. The Ethical Boundary

I reached the database input screen and stopped. I had 100% proof of the RCE. I chose not to proceed because doing so would have interfered with the target's existing data or taken the staging environment offline. I reported the vulnerability immediately, explaining the "Practical Damage" of a full network pivot.

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ha ha ha……!

5. Recognition & The Comeback

This finding was validated and rewarded. You can find my name (Bharath) listed in the recent program update here: Oliver Maicher — Happy Jesus Day Updates.

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Lessons from the Underground

Starting 2026 with a P1 reminded me that the "rust" I feared was actually "rest."

  • Infrastructure matters just as much as code.
  • Staging environments are often the weakest link.
  • Knowledge is power. Two years ago, I might have missed this. Today, it was my path to the top.

The bugs are still there. They're just waiting for you to come back with a better set of eyes.

-I am back Happy New Year.