CWE-1037 Base Incomplete Low likelihood

Processor Optimization Removal or Modification of Security-critical Code

This vulnerability occurs when a processor's performance optimization unintentionally strips out or alters security-critical code that a developer intentionally placed in the software.

Definition

What is CWE-1037?

This vulnerability occurs when a processor's performance optimization unintentionally strips out or alters security-critical code that a developer intentionally placed in the software.
Modern processors use complex optimization techniques like speculative execution, branch prediction, and instruction reordering to boost performance. However, these very optimizations can sometimes work against security by removing timing-based checks, skipping redundant-looking security validations, or executing instructions out of order in a way that bypasses critical security gates. The developer's code appears correct at the source and compiled levels, but the hardware's behavior creates a hidden gap in the intended security model. For developers, this means security mechanisms that rely on precise execution order or constant-time operations—common in cryptography or access control checks—are particularly at risk. Mitigating this requires understanding specific processor behaviors and using appropriate barriers, serializing instructions, or compiler intrinsics that prevent the CPU from optimizing away these sensitive code sections. It's a reminder that security must be enforced at the hardware-software interface, not just within the source code.
Real-world impact

Real-world CVEs caused by CWE-1037

  • CVE-2017-5715

    Intel, ARM, and AMD processor optimizations related to speculative execution and branch prediction cause access control checks to be bypassed when placing data into the cache. Often known as "Spectre".

  • CVE-2017-5753

    Intel, ARM, and AMD processor optimizations related to speculative execution and branch prediction cause access control checks to be bypassed when placing data into the cache. Often known as "Spectre".

  • CVE-2017-5754

    Intel processor optimizations related to speculative execution cause access control checks to be bypassed when placing data into the cache. Often known as "Meltdown".

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-1037

  • 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-1037

White Box Opportunistic

In theory this weakness can be detected through the use of white box testing techniques where specifically crafted test cases are used in conjunction with debuggers to verify the order of statements being executed.

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Frequently asked questions

Frequently asked questions

What is CWE-1037?

This vulnerability occurs when a processor's performance optimization unintentionally strips out or alters security-critical code that a developer intentionally placed in the software.

How serious is CWE-1037?

MITRE rates the likelihood of exploit as Low — exploitation is uncommon, but the weakness should still be fixed when discovered.

What languages or platforms are affected by CWE-1037?

MITRE lists the following affected platforms: Processor Hardware.

How can I prevent CWE-1037?

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-1037?

Plexicus's SAST engine matches the data-flow signature for CWE-1037 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-1037?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/1037.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-1037

CWE-1038 Parent

Insecure Automated Optimizations

This vulnerability occurs when software uses automated tools to optimize code for performance or efficiency, but those optimizations…

CWE-733 Sibling

Compiler Optimization Removal or Modification of Security-critical Code

This vulnerability occurs when a compiler's optimization process unintentionally strips out or alters security-critical code that a…

Resources

Further reading

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