CWE

Common Weakness Enumeration

A community-developed list of SW & HW weaknesses that can become vulnerabilities
New to CWE? click here!
CWE Most Important Hardware Weaknesses
CWE Top 25 Most Dangerous Weaknesses
Home > CWE List > CWE-766: Critical Data Element Declared Public (4.18)
ID
CWE Glossary Definition

CWE-766: Critical Data Element Declared Public

Weakness ID: 766
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.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
×

Edit Custom Filter


Description
The product declares a critical variable, field, or member to be public when intended security policy requires it to be private.
Extended Description

This issue makes it more difficult to maintain the product, which indirectly affects security by making it more difficult or time-consuming to find and/or fix vulnerabilities. It also might make it easier to introduce vulnerabilities.

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; Modify Application Data

Scope: Integrity, Confidentiality

Making a critical variable public allows anyone with access to the object in which the variable is contained to alter or read the value.

Reduce Maintainability

Scope: Other

Potential Mitigations
Phase(s) Mitigation

Implementation
Data should be private, static, and final whenever possible. This will assure that your code is protected by instantiating early, preventing access, and preventing tampering.
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. 732 Incorrect Permission Assignment for Critical Resource
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. 1061 Insufficient Encapsulation
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. 275 Permission 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
Implementation
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

C++ (Undetermined Prevalence)

C# (Undetermined Prevalence)

Java (Undetermined Prevalence)

Demonstrative Examples

Example 1


The following example declares a critical variable public, making it accessible to anyone with access to the object in which it is contained.

(bad code)
Example Language: C++
public: char* password;

Instead, the critical data should be declared private.

(good code)
Example Language: C++
private: char* password;

Even though this example declares the password to be private, there are other possible issues with this implementation, such as the possibility of recovering the password from process memory (CWE-257).



Example 2


The following example shows a basic user account class that includes member variables for the username and password as well as a public constructor for the class and a public method to authorize access to the user account.

(bad code)
Example Language: C++
#define MAX_PASSWORD_LENGTH 15
#define MAX_USERNAME_LENGTH 15

class UserAccount
{
public:
UserAccount(char *username, char *password)
{
if ((strlen(username) > MAX_USERNAME_LENGTH) ||
(strlen(password) > MAX_PASSWORD_LENGTH)) {
ExitError("Invalid username or password");
}
strcpy(this->username, username);
strcpy(this->password, password);
}


int authorizeAccess(char *username, char *password)
{
if ((strlen(username) > MAX_USERNAME_LENGTH) ||
(strlen(password) > MAX_PASSWORD_LENGTH)) {
ExitError("Invalid username or password");
}
// if the username and password in the input parameters are equal to

// the username and password of this account class then authorize access
if (strcmp(this->username, username) ||
strcmp(this->password, password))
return 0;

// otherwise do not authorize access
else
return 1;
}

char username[MAX_USERNAME_LENGTH+1];
char password[MAX_PASSWORD_LENGTH+1];
};

However, the member variables username and password are declared public and therefore will allow access and changes to the member variables to anyone with access to the object. These member variables should be declared private as shown below to prevent unauthorized access and changes.

(good code)
Example Language: C++
class UserAccount
{
public:
...


private:
char username[MAX_USERNAME_LENGTH+1];
char password[MAX_PASSWORD_LENGTH+1];
};


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
variables declared public allow remote read of system properties such as user name and home directory.
Weakness Ordinalities
Ordinality Description
Primary
(where the weakness exists independent of other weaknesses)
Indirect
(where the weakness is a quality issue that might indirectly make it easier to introduce security-relevant weaknesses or make them more difficult to detect)
Detection Methods
Method Details

Automated Static Analysis
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Effectiveness: High
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. 849 The CERT Oracle Secure Coding Standard for Java (2011) Chapter 6 - Object Orientation (OBJ)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1002 SFP Secondary Cluster: Unexpected Entry Points
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1130 CISQ Quality Measures (2016) - Maintainability
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1139 SEI CERT Oracle Secure Coding Standard for Java - Guidelines 05. Object Orientation (OBJ)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1412 Comprehensive Categorization: Poor Coding Practices
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
CLASP Failure to protect stored data from modification
The CERT Oracle Secure Coding Standard for Java (2011) OBJ01-J Declare data members as private and provide accessible wrapper methods
Software Fault Patterns SFP28 Unexpected access points
OMG ASCMM ASCMM-MNT-15
References
[REF-960] Object Management Group (OMG). "Automated Source Code Maintainability Measure (ASCMM)". ASCMM-MNT-15. 2016-01.
<https://www.omg.org/spec/ASCMM/>. (URL validated: 2023年04月07日)
Content History
Submissions
Submission Date Submitter Organization
2009年03月03日
(CWE 1.4, 2009年05月27日) 		CWE Content Team MITRE
Modifications
Modification Date Modifier Organization
2024年02月29日
(CWE 4.14, 2024年02月29日) 		CWE Content Team MITRE
updated Demonstrative_Examples
2023年10月26日 CWE Content Team MITRE
updated Observed_Examples
2023年06月29日 CWE Content Team MITRE
updated Mapping_Notes, Relationships
2023年04月27日 CWE Content Team MITRE
updated Detection_Factors, References, Relationships, Time_of_Introduction, Type
2023年01月31日 CWE Content Team MITRE
updated Description
2020年02月24日 CWE Content Team MITRE
updated Relationships
2019年01月03日 CWE Content Team MITRE
updated Common_Consequences, Description, Name, References, Relationships, Taxonomy_Mappings, Weakness_Ordinalities
2017年11月08日 CWE Content Team MITRE
updated Likelihood_of_Exploit, Relationships
2014年07月30日 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2012年05月11日 CWE Content Team MITRE
updated Relationships
2011年06月01日 CWE Content Team MITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2010年12月13日 CWE Content Team MITRE
updated Observed_Examples
2009年12月28日 CWE Content Team MITRE
updated Demonstrative_Examples
Previous Entry Names
Change Date Previous Entry Name
2019年01月03日 Critical Variable Declared Public
More information is available — Please edit the custom filter or select a different filter.
Page Last Updated: September 09, 2025

Use of the Common Weakness Enumeration (CWE™) and the associated references from this website are subject to the Terms of Use. CWE is sponsored by the U.S. Department of Homeland Security (DHS) Cybersecurity and Infrastructure Security Agency (CISA) and managed by the Homeland Security Systems Engineering and Development Institute (HSSEDI) which is operated by The MITRE Corporation (MITRE). Copyright © 2006–2025, The MITRE Corporation. CWE, CWSS, CWRAF, and the CWE logo are trademarks of The MITRE Corporation.

AltStyle によって変換されたページ (->オリジナル) /