CWE-733: Compiler Optimization Removal or Modification of Security-critical Code

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));                   				 }

Observed CVE Examples (2)

CVE-2008-1685

C compiler optimization, as allowed by specifications, removes code that is used to perform checks to detect integer overflows.

View Details

CVE-2019-1010006

Chain: compiler optimization (CWE-733) removes or modifies code used to detect integer overflow (CWE-190), allowing out-of-bounds write (CWE-787).

View Details

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Detect Compiler Optimization Removal or Modification of Security-critical Code with Black Box

Documented detection approaches include Black Box, and White Box; recorded impacts include Bypass Protection Mechanism, and Alter Execution Logic; the entry maps to CAPEC-10, CAPEC-24, CAPEC-46, and CAPEC-8. Use these source-defined anchors to turn CWE-733 into implementation, review, and verification checks for the affected component.

CWE-733: Compiler Optimization Removal or Modification of Security-critical Code — MITRE CWE

Prevent CWE-733 through an SSDF control plan

Use NIST SSDF practices to make prevention of CWE-733, Compiler Optimization Removal or Modification of Security-critical Code, an explicit development outcome. Translate the CWE definition into security requirements and design constraints, choose safer implementation patterns and toolchain checks, and define acceptance evidence before release. Feed every confirmed occurrence back into the requirements, design review, and coding rules so the same root cause is removed across the product rather than patched in one location.

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

Triage CWE-733 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-733, Compiler Optimization Removal or Modification of Security-critical Code, 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-733

Apply MITRE's full root-cause mapping guidance when using CWE-733, Compiler Optimization Removal or Modification of Security-critical Code. 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-733 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-733, Compiler Optimization Removal or Modification of Security-critical Code. 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-733: Compiler Optimization Removal or Modification of Security-critical Code?+

CWE-733: Compiler Optimization Removal or Modification of Security-critical Code is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The developer builds a security-critical protection mechanism into the software, but the compiler optimizes the program such that the mechanism is removed or modified.

What are the security consequences of Compiler Optimization Removal or Modification of Security-critical Code?+

If exploited, CWE-733 (Compiler Optimization Removal or Modification of Security-critical Code) it can compromise Access Control and Other, leading to outcomes such as Bypass Protection Mechanism and Alter Execution Logic.

How is Compiler Optimization Removal or Modification of Security-critical Code detected?+

CWE-733 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 Optimization Removal or Modification of Security-critical Code?+

CWE-733 commonly affects C, C++ and Compiled. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Compiler Optimization Removal or Modification of Security-critical Code?+

MITRE documents real CVEs mapped to CWE-733, including CVE-2008-1685 and CVE-2019-1010006. 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-733 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-733: Compiler Optimization Removal or Modification of Security-critical Code

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