This specific weakness is impossible to detect using black box methods. While an analyst could examine memory to see that it has not been scrubbed, an analysis of the executable would not be successful. This is because the compiler has already removed the relevant code. Only the source code shows whether the programmer intended to clear the memory or not, so this weakness is indistinguishable from others.
CWE-14 Variant Draft
Compiler Removal of Code to Clear Buffers
A compiler optimization can remove security-critical code intended to wipe sensitive data from memory, leaving secrets exposed. This happens when the compiler identifies buffer-clearing operations…
Definition
What is CWE-14?
A compiler optimization can remove security-critical code intended to wipe sensitive data from memory, leaving secrets exposed. This happens when the compiler identifies buffer-clearing operations as unnecessary 'dead stores' and eliminates them.
This vulnerability occurs in a three-step scenario. First, your application stores confidential information like passwords, encryption keys, or tokens in memory. Then, as a security best practice, your source code explicitly overwrites that memory location to scrub the data. However, an optimizing compiler analyzes the code, sees the memory isn't read again after being overwritten, and decides the overwrite operation is a 'dead store'—a redundant write to a variable that is never used. To improve performance, the compiler silently removes this crucial cleanup instruction from the final executable, leaving the secret data intact in memory where it could be dumped or leaked.
For developers, this is a critical pitfall because your source code appears secure, but the compiled binary behaves differently. You cannot rely on standard memory-zeroing functions in performance-sensitive or optimized release builds without taking special precautions. Mitigating this requires using compiler-specific directives (like `volatile` pointers), dedicated secure memory-wiping functions designed to survive optimization, or disabling specific optimizations for the sensitive code sections to ensure your cleanup logic is executed as intended.
Real-world impact
Real-world CVEs caused by CWE-14
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 1
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().
- 2
The code in the example will behave correctly if it is executed verbatim, but if the code is compiled using an optimizing compiler, such as Microsoft Visual C++ .NET or GCC 3.x, then the call to memset() will be removed as a dead store because the buffer pwd is not used after its value is overwritten [18]. 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.
- 3
It is common practice to overwrite sensitive data manipulated in memory, such as passwords or cryptographic keys, in order to prevent attackers from learning system secrets. However, with the advent of optimizing compilers, programs do not always behave as their source code alone would suggest. In the example, the compiler interprets the call to memset() as dead code because the memory being written to is not subsequently used, despite the fact that there is clearly a security motivation for the operation to occur. The problem here is that many compilers, and in fact many programming languages, do not take this and other security concerns into consideration in their efforts to improve efficiency.
- 4
Attackers typically exploit this type of vulnerability by using a core dump or runtime mechanism to access the memory used by a particular application and recover the secret information. Once an attacker has access to the secret information, it is relatively straightforward to further exploit the system and possibly compromise other resources with which the application interacts.
Vulnerable code example
Vulnerable C
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().
void GetData(char *MFAddr) {
char pwd[64];
if (GetPasswordFromUser(pwd, sizeof(pwd))) {
if (ConnectToMainframe(MFAddr, pwd)) {
```
// Interaction with mainframe*
}}
memset(pwd, 0, sizeof(pwd));} Secure code example
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-14
- Implementation Store the sensitive data in a "volatile" memory location if available.
- Build and Compilation If possible, configure your compiler so that it does not remove dead stores.
- Architecture and Design Where possible, encrypt sensitive data that are used by a software system.
Detection signals
How to detect CWE-14
This weakness is only detectable using white box methods (see black box detection factor). Careful analysis is required to determine if the code is likely to be removed by the compiler.
Plexicus auto-detects CWE-14 and opens a fix PR in under 60 seconds.
Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.
Frequently asked questions What is CWE-14?
How serious is CWE-14?
What languages or platforms are affected by CWE-14?
How can I prevent CWE-14?
How does Plexicus detect and fix CWE-14?
Where can I learn more about CWE-14?
Frequently asked questions
What is CWE-14?
A compiler optimization can remove security-critical code intended to wipe sensitive data from memory, leaving secrets exposed. This happens when the compiler identifies buffer-clearing operations as unnecessary 'dead stores' and eliminates them.
How serious is CWE-14?
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-14?
MITRE lists the following affected platforms: C, C++.
How can I prevent CWE-14?
Store the sensitive data in a "volatile" memory location if available. If possible, configure your compiler so that it does not remove dead stores.
How does Plexicus detect and fix CWE-14?
Plexicus's SAST engine matches the data-flow signature for CWE-14 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-14?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/14.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Resources
Further reading
- MITRE — official CWE-14 https://cwe.mitre.org/data/definitions/14.html
- Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf
- Writing Secure Code https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223
- When scrubbing secrets in memory doesn't work https://seclists.org/bugtraq/2002/Nov/48
- Some Bad News and Some Good News https://learn.microsoft.com/en-us/previous-versions/ms972826(v=msdn.10)
- GNU GCC: Optimizer Removes Code Necessary for Security https://seclists.org/bugtraq/2002/Nov/266
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