CWE - CWE-12: ASP.NET Misconfiguration: Missing Custom Error Page (4.18)

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CWE Glossary Definition

CWE-12: ASP.NET Misconfiguration: Missing Custom Error Page

Weakness ID: 12

Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.

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Description

An ASP .NET application must enable custom error pages in order to prevent attackers from mining information from the framework's built-in responses.

Common Consequences

Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

Impact	Details
Read Application Data	Scope: Confidentiality Default error pages gives detailed information about the error that occurred, and should not be used in production environments. Attackers can leverage the additional information provided by a default error page to mount attacks targeted on the framework, database, or other resources used by the application.

Potential Mitigations

Phase(s)	Mitigation
System Configuration	Handle exceptions appropriately in source code. ASP .NET applications should be configured to use custom error pages instead of the framework default page.
Architecture and Design	Do not attempt to process an error or attempt to mask it.
Implementation	Verify return values are correct and do not supply sensitive information about the system.

Relationships

Section Help This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	756	Missing Custom Error Page

Background Details

The mode attribute of the <customErrors> tag defines whether custom or default error pages are used.

Modes Of Introduction

Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

Phase	Note
Implementation
Operation

Applicable Platforms

Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

ASP.NET (Undetermined Prevalence)

Demonstrative Examples

Example 1

The mode attribute of the <customErrors> tag in the Web.config file defines whether custom or default error pages are used.

In the following insecure ASP.NET application setting, custom error message mode is turned off. An ASP.NET error message with detailed stack trace and platform versions will be returned.

(bad code)

Example Language: ASP.NET

A more secure setting is to set the custom error message mode for remote users only. No defaultRedirect error page is specified. The local user on the web server will see a detailed stack trace. For remote users, an ASP.NET error message with the server customError configuration setting and the platform version will be returned.

(good code)

Example Language: ASP.NET

Another secure option is to set the mode attribute of the <customErrors> tag to use a custom page as follows:

(good code)

Example Language: ASP.NET

Memberships

Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.

Nature	Type	ID	Name
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	2	7PK - Environment
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	731	OWASP Top Ten 2004 Category A10 - Insecure Configuration Management
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	963	SFP Secondary Cluster: Exposed Data
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	1405	Comprehensive Categorization: Improper Check or Handling of Exceptional Conditions

Vulnerability Mapping Notes

Usage ALLOWED

(this CWE ID may be used to map to real-world vulnerabilities)

Reason Acceptable-Use

Rationale

This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
7 Pernicious Kingdoms	ASP.NET Misconfiguration: Missing Custom Error Handling

References

[REF-6] Katrina Tsipenyuk, Brian Chess and Gary McGraw. "Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors". NIST Workshop on Software Security Assurance Tools Techniques and Metrics. NIST. 2005年11月07日.
<https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf>.

[REF-65] M. Howard, D. LeBlanc and J. Viega. "19 Deadly Sins of Software Security". McGraw-Hill/Osborne. 2005年07月26日.

[REF-66] OWASP, Fortify Software. "ASP.NET Misconfiguration: Missing Custom Error Handling".
<https://www.owasp.org/index.php/ASP.NET_Misconfiguration:_Missing_Custom_Error_Handling>.

Content History

Submissions
Submission Date	Submitter	Organization
2006年07月19日 (CWE Draft 3, 2006年07月19日)	7 Pernicious Kingdoms
2006年07月19日 (CWE Draft 3, 2006年07月19日)
Modifications
Modification Date	Modifier	Organization
2025年09月09日 (CWE 4.18, 2025年09月09日)	CWE Content Team	MITRE
2025年09月09日 (CWE 4.18, 2025年09月09日)	updated References
2023年06月29日	CWE Content Team	MITRE
2023年06月29日	updated Mapping_Notes
2023年04月27日	CWE Content Team	MITRE
2023年04月27日	updated Relationships
2020年02月24日	CWE Content Team	MITRE
2020年02月24日	updated References, Relationships
2017年11月08日	CWE Content Team	MITRE
2017年11月08日	updated Demonstrative_Examples, Potential_Mitigations, References, Relationships
2014年07月30日	CWE Content Team	MITRE
2014年07月30日	updated Relationships
2013年02月21日	CWE Content Team	MITRE
2013年02月21日	updated Potential_Mitigations
2012年10月30日	CWE Content Team	MITRE
2012年10月30日	updated Potential_Mitigations
2012年05月11日	CWE Content Team	MITRE
2012年05月11日	updated Demonstrative_Examples, Relationships
2011年06月27日	CWE Content Team	MITRE
2011年06月27日	updated Common_Consequences
2011年06月01日	CWE Content Team	MITRE
2011年06月01日	updated Common_Consequences
2009年07月27日	CWE Content Team	MITRE
2009年07月27日	updated Background_Details, Common_Consequences, Other_Notes
2009年03月10日	CWE Content Team	MITRE
2009年03月10日	updated Name, Relationships
2008年11月24日	CWE Content Team	MITRE
2008年11月24日	updated Common_Consequences, Other_Notes, Potential_Mitigations
2008年10月14日	CWE Content Team	MITRE
2008年10月14日	updated Relationships
2008年09月08日	CWE Content Team	MITRE
2008年09月08日	updated Relationships, Other_Notes, References, Taxonomy_Mappings
2008年07月01日	Eric Dalci	Cigital
2008年07月01日	updated References, Demonstrative_Example, Potential_Mitigations, Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2009年03月10日	ASP.NET Misconfiguration: Missing Custom Error Handling

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Page Last Updated: September 09, 2025

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