CWE-453: Insecure Default Variable Initialization

Code Examples & CVEs

Demonstrative Examples

This code attempts to login a user using credentials from a POST request:

Because the $authorized variable is never initialized, PHP will automatically set $authorized to any value included in the POST request if register_globals is enabled. An attacker can send a POST request with an unexpected third value 'authorized' set to 'true' and gain authorized status without supplying valid credentials.

BadPHP

// $user and $pass automatically set from POST request                      if (login_user($user,$pass)) {$authorized = true;}                      ...                                            if ($authorized) {generatePage();}

This code attempts to login a user using credentials from a POST request:

GoodPHP

$user = $_POST['user'];$pass = $_POST['pass'];$authorized = false;if (login_user($user,$pass)) {$authorized = true;}                      ...

Observed CVE Examples (1)

CVE-2022-36349

insecure default variable initialization in BIOS firmware for a hardware board allows DoS

View Details

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-453 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-453, Insecure Default Variable Initialization, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Insecure Default Variable Initialization during System Configuration

MITRE associates mitigation with System Configuration; documented detection approaches include Automated Static Analysis; recorded impacts include Modify Application Data. Use these source-defined anchors to turn CWE-453 into implementation, review, and verification checks for the affected component.

CWE-453: Insecure Default Variable Initialization — MITRE CWE

Triage CWE-453 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-453, Insecure Default Variable Initialization, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-453

Apply MITRE's full root-cause mapping guidance when using CWE-453, Insecure Default Variable Initialization. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-453 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-453, Insecure Default Variable Initialization. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-453: Insecure Default Variable Initialization?+

CWE-453: Insecure Default Variable Initialization is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product, by default, initializes an internal variable with an insecure or less secure value than is possible.

What are the security consequences of Insecure Default Variable Initialization?+

If exploited, CWE-453 (Insecure Default Variable Initialization) it can compromise Integrity, leading to outcomes such as Modify Application Data.

How do you prevent or mitigate Insecure Default Variable Initialization?+

Recommended mitigations for CWE-453 include: Disable or change default settings when they can be used to abuse the system. Since those default settings are shipped with the product they are likely to be known by a potential attacker who is familiar with the product. For instance, default credentials should be changed or the associated accounts should be disabled.

Which programming languages are affected by Insecure Default Variable Initialization?+

CWE-453 commonly affects PHP and Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Insecure Default Variable Initialization?+

MITRE documents real CVEs mapped to CWE-453, including CVE-2022-36349. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-453 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-453: Insecure Default Variable Initialization

Technical Details

Applicable To

Security Consequences

Scope

Impact

Mitigation Strategies

Phase

Description

Detection Methods