CWE-14: Compiler Removal of Code to Clear Buffers

Extended Description

This compiler optimization error occurs when: Secret data are stored in memory. The secret data are scrubbed from memory by overwriting its contents. The source code is compiled using an optimizing compiler, which identifies and removes the function that overwrites the contents as a dead store because the memory is not used subsequently.

Code Examples & CVEs

Demonstrative Examples

The following code reads a password from the user, uses the password to connect to a back-end mainframe, and then attempts to scrub the password from memory using memset().

The code in the example will behave correctly if it is executed verbatim, but if the code is compiled using an optimizing compiler, then the call to memset() might be removed as a dead store, because the buffer pwd is not used after its value is overwritten. Because the buffer pwd contains a sensitive value, the application may be vulnerable to attack if the data are left memory resident. If attackers are able to access the correct region of memory, they may use the recovered password to gain control of the system.

BadC

void GetData(char *MFAddr) { 				  				   char pwd[64]; 				   if (GetPasswordFromUser(pwd, sizeof(pwd))) { 				    					 if (ConnectToMainframe(MFAddr, pwd)) { 					  					   // Interaction with mainframe 					  					 } 				    				   } 				   memset(pwd, 0, sizeof(pwd));                   				 }

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-14 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-14, Compiler Removal of Code to Clear Buffers, 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 Compiler Removal of Code to Clear Buffers during Implementation

MITRE associates mitigation with Implementation, Build and Compilation, and Architecture and Design; documented detection approaches include Black Box, and White Box; recorded impacts include Read Memory, and Bypass Protection Mechanism. Use these source-defined anchors to turn CWE-14 into implementation, review, and verification checks for the affected component.

CWE-14: Compiler Removal of Code to Clear Buffers — MITRE CWE

Triage CWE-14 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-14, Compiler Removal of Code to Clear Buffers, 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-14

Apply MITRE's full root-cause mapping guidance when using CWE-14, Compiler Removal of Code to Clear Buffers. 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-14 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-14, Compiler Removal of Code to Clear Buffers. 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-14: Compiler Removal of Code to Clear Buffers?+

CWE-14: Compiler Removal of Code to Clear Buffers is a Common Weakness Enumeration (CWE) entry maintained by MITRE. Sensitive memory is cleared according to the source code, but compiler optimizations leave the memory untouched when it is not read from again, aka "dead store removal." This compiler optimization error occurs when: Secret data are stored in memory. The secret data are scrubbed from memory by overwriting its contents. The source code is compiled using an optimizing compiler, which identifies and removes the function that overwrites the contents as a dead store because the memory is not used subsequently.

What are the security consequences of Compiler Removal of Code to Clear Buffers?+

If exploited, CWE-14 (Compiler Removal of Code to Clear Buffers) it can compromise Confidentiality and Access Control, leading to outcomes such as Read Memory and Bypass Protection Mechanism.

How do you prevent or mitigate Compiler Removal of Code to Clear Buffers?+

Recommended mitigations for CWE-14 include: Store the sensitive data in a "volatile" memory location if available. If possible, configure your compiler so that it does not remove dead stores. Where possible, encrypt sensitive data that are used by a software system.

How is Compiler Removal of Code to Clear Buffers detected?+

CWE-14 can be detected using Black Box and White Box. Combining automated tooling with manual review typically yields the best coverage.

Which programming languages are affected by Compiler Removal of Code to Clear Buffers?+

CWE-14 commonly affects C, C++ and Compiled. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

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

A CWE (Common Weakness Enumeration) like CWE-14 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-14: Compiler Removal of Code to Clear Buffers

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Code Examples & CVEs

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Source-backed guidance

Verify controls for CWE-14 with SSDF evidence

Address Compiler Removal of Code to Clear Buffers during Implementation

Triage CWE-14 against known exploitation evidence

Apply precise root-cause mapping to CWE-14

Validate CWE-14 with root-cause mapping checks

Frequently Asked Questions

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