CWE-200 Weakness: Full Overview

CVEs are Common Vulnerabilities and Exposures - unique identifiers assigned to publicly known cybersecurity vulnerabilities. CWEs (Common Weakness Enumerations) represent the underlying categories of these flaws.

CWE-200, formally known as Exposure of Sensitive Information to an Unauthorized Actor, is a foundational software weakness that consistently ranks in the CWE Top 25 Most Dangerous Software Weaknesses.

Unlike a specific exploit that breaks a lock, CWE-200 is akin to leaving the window transparent: it unintentionally reveals internal system details, user credentials, or configuration data to anyone who asks. This "chatter" often provides the vital intelligence attackers need to launch more devastating targeted attacks.

This page explains the mechanics of this weakness, highlights recent critical examples from 2025, and details how to silence your noisy applications.

What is CWE-200 weakness?

CWE-200 occurs when a product explicitly or unintentionally violates the principle of confidentiality. It happens when software provides sensitive information to an actor—such as a user, a specific process, or an external system—that is not authorized to see it.

This is a broad category that covers everything from:

• Verbose Error Messages: Displaying full stack traces or database queries to end-users.

• Data Leaks: API endpoints that return more data fields (like passwords or keys) than the UI displays.

• Banner Grabbing: Server headers revealing specific software versions (e.g., "Apache/2.4.50").

It is rated highly dangerous because it is a "precursor" vulnerability; the information gathered here is almost always used to fuel further exploitation.

When was it defined?

CWE-200 was established in the original CWE list in 2006. However, it remains a persistent threat in modern software. In the 2024-2025 reporting period, it rose significantly in the Top 25 rankings due to the increasing complexity of cloud APIs and microservices.

Recent notable examples (2025)

While CWE-200 is a category, it manifests in specific vulnerabilities. The following recent high-profile CVEs are direct instances of CWE-200:

CWE-200 technical description

The weakness stems from a mismatch between the data an application has and the data it should share.

In a typical scenario (like the Argo CD example above), an application might process a request for a "Project Details" object. The backend database holds the project's name, description, and the secret keys used to deploy it. If the API code simply serializes the entire database object to JSON and sends it to the client—relying on the frontend to hide the secret fields—the attacker can simply intercept the raw network traffic to see the keys.

Common vectors include:

• Uncleansed Logging: Writing passwords or session tokens into plain-text log files.

• Discrepancy Information: Revealing whether a username exists based on how long the login process takes (Timing Attacks) or different error messages.

Tactics, techniques & procedures (TTPs)

Attackers exploit CWE-200 primarily during the Reconnaissance and Discovery phases of the kill chain.

• Active Probing: Attackers send malformed data to web forms to trigger stack traces (e.g., SQL errors) that reveal database structure and versioning.

• API Fuzzing: Manipulating API calls to see if endpoints return "hidden" fields (Shadow APIs).

• Log Analysis: In post-compromise scenarios (like the FortiADC case), attackers with low-level access read logs to find credentials for lateral movement.

• Banner Grabbing: Simply connecting to a port (e.g., Telnet or HTTP) to read the default "Welcome" banner, which often announces the exact OS and service version.

Indicators of compromise

Detecting exploitation of CWE-200 is difficult because the traffic often looks legitimate. However, signs include:

• Anomalous Scans: A spike in traffic resulting in 4xx or 5xx error codes, indicating an attacker is trying to force the application to "break" and reveal info.

• Data Volume Spikes: API responses that are significantly larger than average, suggesting an endpoint is dumping more data than intended (e.g., a full database table dump).

• Log Reviews: Finding sensitive strings (like "password=", "key=", or "token=") in your own application or firewall logs—if you can see them, an attacker who gains access to those logs can too.

How to detect CWE-200 weakness?

• Dynamic Application Security Testing (DAST): Tools like OWASP ZAP or Burp Suite can identify verbose error messages and sensitive data in HTTP responses.

• Static Analysis (SAST): Code scanners can catch patterns where sensitive variables are written to logs or standard output.

• Manual Penetration Testing: Human testers are essential for identifying "logic" leaks, such as an IDOR vulnerability where changing an ID number reveals another user's PII.

Impact & risk of CWE-200 weakness

The risk is variable but often High.

While an information leak might not crash a server directly, it is the fuel for the fire. Exposing a software version allows attackers to look up specific exploits for that version. Exposing a password or API key (as seen in CVE-2025-55190) can lead to an immediate, full system compromise.

Mitigation & remediation strategies

Defense against CWE-200 requires a "Need-to-Know" architecture:

• Generic Error Messages: Configure web servers and applications to display generic error pages (e.g., "An error occurred") rather than technical stack traces. Log the details internally instead.

• Data Sanitization (DTOs): Use Data Transfer Objects (DTOs) in your code to explicitly define what data is sent to the user. Never serialize a raw database object directly to an API response.

• Least Privilege Logging: Ensure developers are trained not to log sensitive data. Implement log scrubbing tools to automatically redact patterns that look like credit card numbers or keys.

• Disable Banners: Configure services (SSH, HTTP, FTP) to suppress version banners. "Security by obscurity" is not a standalone defense, but giving away your exact version number is unnecessary assistance to an attacker.

[[FAQ]] CWE-200 Weakness FAQs

[[Q]] What is the difference between CWE-200 and a CVE?

[[A]] CWE-200 is the category of the weakness (Information Exposure). A CVE (Common Vulnerabilities and Exposures) is a specific instance of that weakness in a specific product. For example, CVE-2025-55190 is a specific CWE-200 flaw in Argo CD.

[[Q]] Is exposing a software version really a security risk?

[[A]] Yes. While it doesn't grant access by itself, it saves attackers time. If an attacker knows you are running "Apache 2.4.49", they know exactly which "Path Traversal" exploits will work against you, allowing them to launch a targeted attack immediately.

[[Q]] How do I fix CWE-200 in my own code?

[[A]] You must explicitly control what you output. Never trust default serialization. Create specific "View" models that only contain the data the user needs to see, and strip out everything else (internal IDs, passwords, system paths) before the data leaves the server.

[[Q]] Can automated tools find all CWE-200 flaws?

[[A]] No. Automated tools are good at finding technical leaks (like stack traces), but they struggle with logical leaks (like an API returning another user's email address). Manual review and logic testing are critical.