CWE - CWE-421: Race Condition During Access to Alternate Channel (4.18)

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CWE Glossary Definition

CWE-421: Race Condition During Access to Alternate Channel

Weakness ID: 421

Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: 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.

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Description

The product opens an alternate channel to communicate with an authorized user, but the channel is accessible to other actors.

Extended Description

This creates a race condition that allows an attacker to access the channel before the authorized user does.

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
Gain Privileges or Assume Identity; Bypass Protection Mechanism	Scope: Access Control

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	Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	362	Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
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.	420	Unprotected Alternate Channel

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category Category - a CWE entry that contains a set of other entries that share a common characteristic.	557	Concurrency Issues

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
Architecture and Design

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

Class: Not Language-Specific (Undetermined Prevalence)

Selected Observed Examples

Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.

Reference	Description
CVE-1999-0351	FTP "Pizza Thief" vulnerability. Attacker can connect to a port that was intended for use by another client.
CVE-2003-0230	Product creates Windows named pipe during authentication that another attacker can hijack by connecting to it.

Functional Areas

Program Invocation

Affected Resources

System Process

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.	956	SFP Secondary Cluster: Channel Attack
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	1396	Comprehensive Categorization: Access Control

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 Base 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
PLOVER	Alternate Channel Race Condition

References

[REF-354] Blake Watts. "Discovering and Exploiting Named Pipe Security Flaws for Fun and Profit". 2002-04.
<https://www.blakewatts.com/blog/discovering-and-exploiting-named-pipe-security-flaws-for-fun-and-profit>. (URL validated: 2023年04月07日)

[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 13: Race Conditions." Page 205. McGraw-Hill. 2010.

Content History

Submissions
Submission Date	Submitter	Organization
2006年07月19日 (CWE Draft 3, 2006年07月19日)	PLOVER
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 Functional_Areas
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 References, Relationships
2020年02月24日	CWE Content Team	MITRE
2020年02月24日	updated Relationships
2017年11月08日	CWE Content Team	MITRE
2017年11月08日	updated Applicable_Platforms, Relationships
2014年07月30日	CWE Content Team	MITRE
2014年07月30日	updated Relationships
2014年06月23日	CWE Content Team	MITRE
2014年06月23日	updated Other_Notes
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 References, Relationships
2011年06月01日	CWE Content Team	MITRE
2011年06月01日	updated Common_Consequences
2009年01月12日	CWE Content Team	MITRE
2009年01月12日	updated References
2008年10月14日	CWE Content Team	MITRE
2008年10月14日	updated Description
2008年09月08日	CWE Content Team	MITRE
2008年09月08日	updated Relationships, Observed_Example, Other_Notes, Taxonomy_Mappings, Type
2008年07月01日	Eric Dalci	Cigital
2008年07月01日	updated Potential_Mitigations, Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008年04月11日	Alternate Channel Race Condition

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Page Last Updated: September 09, 2025

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