CWE-1063 Base Incomplete

Creation of Class Instance within a Static Code Block

This weakness occurs when a class instance is created inside a static initializer block, causing premature and potentially expensive object creation.

Definition

What is CWE-1063?

This weakness occurs when a class instance is created inside a static initializer block, causing premature and potentially expensive object creation.
This pattern flags when a static code block—which executes when a class is first loaded—creates an object or performs complex initialization. This forces the program to allocate resources and run constructors earlier than necessary, which can delay application startup and increase memory usage regardless of whether the object is ever actually used. From a security perspective, if an attacker can trigger the loading of this class, they can exploit this forced initialization to cause performance degradation or resource exhaustion, potentially leading to a denial-of-service (DoS) condition. Developers should refactor this to use lazy initialization, creating the instance only when it's first needed within a method.
Real-world impact

Real-world CVEs caused by CWE-1063

No public CVE references are linked to this CWE in MITRE's catalog yet.

How attackers exploit it

Step-by-step attacker path

  1. 1

    Identify a code path that handles untrusted input without validation.

  2. 2

    Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.

  3. 3

    Deliver the payload through a normal request and observe the application's reaction.

  4. 4

    Iterate until the response leaks data, executes attacker code, or escalates privileges.

Vulnerable code example

Vulnerable pseudo

MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.

Vulnerable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Secure code example

Secure pseudo

Secure pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist

How to prevent CWE-1063

  • Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
  • Implementation Validate input at trust boundaries; use allowlists, not denylists.
  • Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
  • Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
  • Operation Monitor logs for the runtime signals listed in the next section.
Detection signals

How to detect CWE-1063

SAST High

Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.

DAST Moderate

Run dynamic application security testing against the live endpoint.

Runtime Moderate

Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.

Code review Moderate

Code review: flag any new code that handles input from this surface without using the validated framework helpers.

Plexicus auto-fix

Plexicus auto-detects CWE-1063 and opens a fix PR in under 60 seconds.

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Frequently asked questions

Frequently asked questions

What is CWE-1063?

This weakness occurs when a class instance is created inside a static initializer block, causing premature and potentially expensive object creation.

How serious is CWE-1063?

MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.

What languages or platforms are affected by CWE-1063?

MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.

How can I prevent CWE-1063?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

How does Plexicus detect and fix CWE-1063?

Plexicus's SAST engine matches the data-flow signature for CWE-1063 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.

Where can I learn more about CWE-1063?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/1063.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-1063

CWE-1176 Parent

Inefficient CPU Computation

This weakness occurs when software uses inefficient algorithms or suboptimal CPU operations, performing unnecessary or overly complex…

CWE-1042 Sibling

Static Member Data Element outside of a Singleton Class Element

This weakness occurs when a class that isn't designed as a singleton (a class meant to have only one instance) contains a non-final static…

CWE-1046 Sibling

Creation of Immutable Text Using String Concatenation

This weakness occurs when code builds a string within a loop using simple concatenation (like +=), which unintentionally creates new…

CWE-1049 Sibling

Excessive Data Query Operations in a Large Data Table

This weakness occurs when an application runs a database query that uses numerous joins and sub-queries on a very large table, leading to…

CWE-1067 Sibling

Excessive Execution of Sequential Searches of Data Resource

This weakness occurs when a database query is structured in a way that forces the system to scan entire tables row-by-row, instead of…

Resources

Further reading

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