What CVEs are caused by CWE-457?

139 recorded CVEs are attributed to CWE-457, including CVE-2026-6748, CVE-2024-32611, CVE-2022-40510.

What are the consequences of CWE-457?

Exploiting CWE-457 can lead to: Other.

Is CWE-457 actively exploited?

139 recorded CVEs are caused by CWE-457; none are currently in CISA's KEV catalog of actively exploited flaws.

Variant weakness

Draft

CWE-457: Use of Uninitialized Variable

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

Last updated May 1, 2026

139

Recorded CVEs

With this primary weakness

KEVs

In the CISA KEV catalog

High

Likelihood of exploit

Per MITRE

Variant

Abstraction

MITRE classification

Overview

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.

Real-world CVEs

139 recorded CVEs are caused by CWE-457 (Use of Uninitialized Variable). The highest-severity and most recent are shown first. 34 new CWE-457 CVEs have been recorded so far in 2026 (36 in 2025).

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Common consequences

What can happen when CWE-457 is exploited.

Other

Affects: Availability, Integrity, Other

Initial variables usually contain junk, which can not be trusted for consistency. This can lead to denial of service conditions, or modify control flow in unexpected ways. In some cases, an attacker can "pre-initialize" the variable using previous actions, which might enable code execution. This can cause a race condition if a lock variable check passes when it should not.

Other

Affects: Authorization, Other

Strings that are not initialized are especially dangerous, since many functions expect a null at the end -- and only at the end -- of a string.

How it happens

When it is introduced

Typically introduced during these phases of the software lifecycle.

Implementation

Applies to

Languages

C (Sometimes)

C++ (Sometimes)

Perl (Often)

PHP (Often)

How to prevent it

Practical mitigations for CWE-457, grouped by where in the lifecycle they apply.

Implementation

Attack Surface Reduction

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

Build and Compilation

Compilation or Build Hardening

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

Language Selection

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.

How to detect it

Fuzzing

Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.

Effectiveness: High

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

Code examples

Illustrative examples from MITRE showing how the weakness appears in code.

This code prints a greeting using information stored in a POST request:

Vulnerable example

php

if (isset($_POST['names'])) {

This code checks if the POST array 'names' is set before assigning it to the $nameArray variable. However, if the array is not in the POST request, $nameArray will remain uninitialized. This will cause an error when the array is accessed to print the greeting message, which could lead to further exploit.

The following switch statement is intended to set the values of the variables aN and bN before they are used:

Vulnerable example

int aN, Bn;

In the default case of the switch statement, the programmer has accidentally set the value of aN twice. As a result, bN will have an undefined value. Most uninitialized variable issues result in general software reliability problems, but if attackers can intentionally trigger the use of an uninitialized variable, they might be able to launch a denial of service attack by crashing the program. Under the right circumstances, an attacker may be able to control the value of an uninitialized variable by affecting the values on the stack prior to the invocation of the function.

This example will leave test_string in an unknown condition when i is the same value as err_val, because test_string is not initialized (CWE-456). Depending on where this code segment appears (e.g. within a function body), test_string might be random if it is stored on the heap or stack. If the variable is declared in static memory, it might be zero or NULL. Compiler optimization might contribute to the unpredictability of this address.

Vulnerable example

test_string = "Hello World!";

Safe example

test_string = "Hello World!";

Illustrative examples

Real CVEs that MITRE cites as examples of this weakness.

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.

Terminology & mappings

Mapped taxonomies

CLASP: Uninitialized variable
7 Pernicious Kingdoms: Uninitialized Variable
Software Fault Patterns: Glitch in computation (SFP1)
SEI CERT Perl Coding Standard: Declare identifiers before using them (DCL33-PL) — Imprecise fit

Frequently asked questions

Common questions about CWE-457.

What is CWE-457?: The code uses a variable that has not been initialized, leading to unpredictable or unintended results.
What CVEs are caused by CWE-457?: 139 recorded CVEs are attributed to CWE-457, including CVE-2026-6748, CVE-2024-32611, CVE-2022-40510.
How do you prevent CWE-457?: Ensure that critical variables are initialized before first use [REF-1485].
How is CWE-457 detected?: Fuzzing: Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
What are the consequences of CWE-457?: Exploiting CWE-457 can lead to: Other.
Is CWE-457 actively exploited?: 139 recorded CVEs are caused by CWE-457; none are currently in CISA's KEV catalog of actively exploited flaws.

References

Weakness data is sourced from the MITRE CWE catalog (v4.20). CVE associations are aggregated and kept current by RadicalNotion.AI.

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Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

Applies to

How to prevent it

How to detect it

Fuzzing

Automated Static Analysis

Code examples

Illustrative examples

Related weaknesses

Parent

Related

Terminology & mappings

Mapped taxonomies

Frequently asked questions

References

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