CWE-457

Use of Uninitialized Variable

Variant

Draft

Description

The code uses a variable that has not been initialized, leading to unpredictable or unintended results.

In some languages such as C and C++, stack variables are not initialized by default. They generally contain junk data with the contents of stack memory before the function was invoked. An attacker can sometimes control or read these contents. In other languages or conditions, a variable that is not explicitly initialized can be given a default value that has security implications, depending on the logic of the program. The presence of an uninitialized variable can sometimes indicate a typographic error in the code.

Parent Weaknesses (ChildOf)

CWE-665: Improper Initialization...

CWE-908: Use of Uninitialized Resource...

Common Consequences

Scope

Availability

Integrity

Other

Impact

Other

Scope

Authorization

Other

Impact

Other

Potential Mitigations

Implementation

Ensure that critical variables are initialized before first use [REF-1485].

Build and Compilation

Most compilers will complain about the use of uninitialized variables if warnings are turned on.

Implementation

Operation

When using a language that does not require explicit declaration of variables, run or compile the software in a mode that reports undeclared or unknown variables. This may indicate the presence of a typographic error in the variable's name.

Requirements

Choose a language that is not susceptible to these issues.

Architecture and Design

Mitigating technologies such as safe string libraries and container abstractions could be introduced.

CVE-2019-15900

Chain: sscanf() call is used to check if a username and group exists, but the return value of sscanf() call is not checked (CWE-252), causing an uninitialized variable to be checked (CWE-457), returning success to allow authorization bypass for executing a privileged (CWE-863).

CVE-2008-3688

Chain: A denial of service may be caused by an uninitialized variable (CWE-457) allowing an infinite loop (CWE-835) resulting from a connection to an unresponsive server.

CVE-2008-0081

Uninitialized variable leads to code execution in popular desktop application.

CVE-2007-4682

Crafted input triggers dereference of an uninitialized object pointer.

CVE-2007-3468

Crafted audio file triggers crash when an uninitialized variable is used.

CVE-2007-2728

Uninitialized random seed variable used.