Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
CWE-211 Base Incomplete
Externally-Generated Error Message Containing Sensitive Information
This vulnerability occurs when an application triggers an error message from an external component—like a database, interpreter, or operating system—and that error reveals sensitive details about…
Definition
What is CWE-211?
This vulnerability occurs when an application triggers an error message from an external component—like a database, interpreter, or operating system—and that error reveals sensitive details about the system's internal workings, configuration, or data.
Unlike application-controlled errors, these messages originate from underlying platforms or dependencies and often include technical details developers didn't intend to expose. Attackers can deliberately trigger these errors by sending malformed inputs or causing system failures, then harvest information like stack traces, file paths, database schemas, or server versions to plan further attacks.
Preventing this requires a defense-in-depth approach: configure external components to suppress verbose errors in production, implement centralized exception handling to catch and sanitize all external messages before they reach users, and ensure logging systems capture detailed diagnostics separately without exposing them through user interfaces. Regular testing with fuzzing and penetration testing helps identify what information leaks through these indirect channels.
Real-world impact
Real-world CVEs caused by CWE-211
-
chain: product does not protect against direct request of an include file, leading to resultant path disclosure when the include file does not successfully execute.
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Single "'" inserted into SQL query leads to invalid SQL query execution, triggering full path disclosure. Possibly resultant from more general SQL injection issue.
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chain: product does not protect against direct request of a library file, leading to resultant path disclosure when the file does not successfully execute.
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invalid parameter triggers a failure to find an include file, leading to infoleak in error message.
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Various invalid requests lead to information leak in verbose error messages describing the failure to instantiate a class, open a configuration file, or execute an undefined function.
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Improper handling of filename request with trailing "/" causes multiple consequences, including information leak in Visual Basic error message.
How attackers exploit it
Step-by-step attacker path
- 1
The following servlet code does not catch runtime exceptions, meaning that if such an exception were to occur, the container may display potentially dangerous information (such as a full stack trace).
- 2
In the following Java example the class InputFileRead enables an input file to be read using a FileReader object. In the constructor of this class a default input file path is set to some directory on the local file system and the method setInputFile must be called to set the name of the input file to be read in the default directory. The method readInputFile will create the FileReader object and will read the contents of the file. If the method setInputFile is not called prior to calling the method readInputFile then the File object will remain null when initializing the FileReader object. A Java RuntimeException will be raised, and an error message will be output to the user.
- 3
However, the error message output to the user contains information regarding the default directory on the local file system. This information can be exploited and may lead to unauthorized access or use of the system. Any Java RuntimeExceptions that are handled should not expose sensitive information to the user.
Vulnerable code example
Vulnerable Java
The following servlet code does not catch runtime exceptions, meaning that if such an exception were to occur, the container may display potentially dangerous information (such as a full stack trace).
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username = request.getParameter("username");
```
// May cause unchecked NullPointerException.*
if (username.length() < 10) {
```
...
}
} Secure code example
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-211
- System Configuration Configure the application's environment in a way that prevents errors from being generated. For example, in PHP, disable display_errors.
- Implementation / Build and Compilation Debugging information should not make its way into a production release.
- Implementation / Build and Compilation Debugging information should not make its way into a production release.
- Implementation Handle exceptions internally and do not display errors containing potentially sensitive information to a user. Create default error pages if necessary.
- Implementation The best way to prevent this weakness during implementation is to avoid any bugs that could trigger the external error message. This typically happens when the program encounters fatal errors, such as a divide-by-zero. You will not always be able to control the use of error pages, and you might not be using a language that handles exceptions.
Detection signals
How to detect CWE-211
Run dynamic application security testing against the live endpoint.
Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.
Code review: flag any new code that handles input from this surface without using the validated framework helpers.
CWE-211
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Frequently asked questions What is CWE-211?
How serious is CWE-211?
What languages or platforms are affected by CWE-211?
How can I prevent CWE-211?
How does Plexicus detect and fix CWE-211?
Where can I learn more about CWE-211?
Frequently asked questions
What is CWE-211?
This vulnerability occurs when an application triggers an error message from an external component—like a database, interpreter, or operating system—and that error reveals sensitive details about the system's internal workings, configuration, or data.
How serious is CWE-211?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-211?
MITRE lists the following affected platforms: PHP.
How can I prevent CWE-211?
Configure the application's environment in a way that prevents errors from being generated. For example, in PHP, disable display_errors. Debugging information should not make its way into a production release.
How does Plexicus detect and fix CWE-211?
Plexicus's SAST engine matches the data-flow signature for CWE-211 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-211?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/211.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-211
CWE-209 Parent
Generation of Error Message Containing Sensitive Information
This vulnerability occurs when an application reveals sensitive details about its internal systems, user data, or environment within error…
CWE-210 Sibling
Self-generated Error Message Containing Sensitive Information
This vulnerability occurs when an application detects a problem and generates its own error messages that accidentally expose sensitive…
CWE-550 Sibling
Server-generated Error Message Containing Sensitive Information
This vulnerability occurs when a web application or server returns detailed error messages that reveal sensitive internal information…
CWE-535 Child
Exposure of Information Through Shell Error Message
This vulnerability occurs when a web application's command shell returns detailed error messages to users. Attackers can analyze these…
CWE-536 Child
Servlet Runtime Error Message Containing Sensitive Information
This vulnerability occurs when a Java servlet application displays detailed runtime error messages that reveal sensitive information about…
CWE-537 Child
Java Runtime Error Message Containing Sensitive Information
This vulnerability occurs when a Java application's runtime error messages reveal sensitive details about the system, such as file paths,…
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