Because byte ordering bugs are usually very noticeable even with normal inputs, this bug is more likely to occur in rarely triggered error conditions, making them difficult to detect using black box methods.
CWE-198 Variant Draft
Use of Incorrect Byte Ordering
This vulnerability occurs when software processes data from another system without considering byte order (endianness), such as big-endian or little-endian. This mismatch can cause the program to…
Definition
What is CWE-198?
This vulnerability occurs when software processes data from another system without considering byte order (endianness), such as big-endian or little-endian. This mismatch can cause the program to misinterpret numbers or values, leading to incorrect calculations, crashes, or security flaws.
At its core, this issue is a data representation mismatch. Different computer architectures store multi-byte data (like integers or memory addresses) in opposite orders. Big-endian stores the most significant byte first, while little-endian stores it last. When software assumes one format but receives data in the other, it reads values backwards, turning a harmless number into a potentially dangerous or logic-breaking one.
To prevent this, developers must explicitly define and validate the byte order for any data crossing trust boundaries, such as in network protocols, file parsers, or inter-process communication. Always use standardized conversion functions (like `ntohl()` or `htons()`) for network data, and consider employing structured data formats with built-in serialization that handles these details automatically.
Real-world impact
Real-world CVEs caused by CWE-198
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 1
Identify a code path that handles untrusted input without validation.
- 2
Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.
- 3
Deliver the payload through a normal request and observe the application's reaction.
- 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.
// 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
// 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-198
- 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-198
CWE-198
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Frequently asked questions What is CWE-198?
How serious is CWE-198?
What languages or platforms are affected by CWE-198?
How can I prevent CWE-198?
How does Plexicus detect and fix CWE-198?
Where can I learn more about CWE-198?
Frequently asked questions
What is CWE-198?
This vulnerability occurs when software processes data from another system without considering byte order (endianness), such as big-endian or little-endian. This mismatch can cause the program to misinterpret numbers or values, leading to incorrect calculations, crashes, or security flaws.
How serious is CWE-198?
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-198?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-198?
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-198?
Plexicus's SAST engine matches the data-flow signature for CWE-198 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-198?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/198.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-198
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