The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.

Primary

Resultant

Architecture and Design

Implementation
REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Confidentiality
Read Files or Directories
Read Memory
Read Application Data
Sensitive data may be exposed to attackers.

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.)
High

Requirements
Specify which data in the software should be regarded as sensitive. Consider which types of users should have access to which types of data.

Implementation
Ensure that any possibly sensitive data specified in the requirements is verified with designers to ensure that it is either a calculated risk or mitigated elsewhere. Any information that is not necessary to the functionality should be removed in order to lower both the overhead and the possibility of security sensitive data being sent.

System Configuration
Setup default error messages so that unexpected errors do not disclose sensitive information.

Architecture and Design
Separation of Privilege

Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

The following is an actual MySQL error statement:

Warning: mysql_pconnect(): Access denied for user: 'root@localhost' (Using password: N1nj4) in /usr/local/www/wi-data/includes/database.inc on line 4

The error clearly exposes the database credentials.

CVE-2022-0708
Collaboration platform does not clear team emails in a response, allowing leak of email addresses
https://www.cve.org/CVERecord?id=CVE-2022-0708

Accidental leaking of sensitive information through sent data

Allowed
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.
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.

Sensitive information could include data that is sensitive in and of itself (such as credentials or private messages), or otherwise useful in the further exploitation of the system (such as internal file system structure).

CLASP
2006-07-19
Draft 3
2006-07-19

Eric Dalci
Cigital
2008-07-01
updated Potential_Mitigations, Time_of_Introduction

CWE Content Team
MITRE
2008-09-08
updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings

CWE Content Team
MITRE
2009-10-29
updated Other_Notes, Potential_Mitigations

CWE Content Team
MITRE
2010-09-27
updated Common_Consequences, Description, Name

CWE Content Team
MITRE
2010-12-13
updated Common_Consequences

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences

CWE Content Team
MITRE
2012-05-11
updated Relationships

CWE Content Team
MITRE
2012-10-30
updated Potential_Mitigations

CWE Content Team
MITRE
2013-02-21
updated Potential_Mitigations

CWE Content Team
MITRE
2014-02-18
updated Related_Attack_Patterns

CWE Content Team
MITRE
2014-07-30
updated Demonstrative_Examples, Relationships

CWE Content Team
MITRE
2017-01-19
updated Related_Attack_Patterns

CWE Content Team
MITRE
2017-11-08
updated Applicable_Platforms, Modes_of_Introduction, Relationships

CWE Content Team
MITRE
2020-02-24
updated Demonstrative_Examples, Description, Name, References, Relationships, Type

CWE Content Team
MITRE
2020-08-20
updated Description, Name

CWE Content Team
MITRE
2020-12-10
updated Potential_Mitigations

CWE Content Team
MITRE
2021-10-28
updated Relationships

CWE Content Team
MITRE
2022-10-13
updated Observed_Examples

CWE Content Team
MITRE
2023-04-27
updated Detection_Factors, Relationships, Time_of_Introduction

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2024-11-19
4.16
2024-11-19
updated Description, Diagram, Other_Notes

CWE Content Team
MITRE
2025-12-11
4.19
2025-12-11
updated Relationships, Weakness_Ordinalities

Information Leak Through Sent Data
Information Exposure Through Sent Data
Exposure of Sensitive Information Through Sent Data