CWE-75 Class Draft

Failure to Sanitize Special Elements into a Different Plane (Special Element Injection)

This vulnerability occurs when an application fails to properly filter or encode user-supplied data containing special characters or commands that can be interpreted in a different context, such as…

Definition

What is CWE-75?

This vulnerability occurs when an application fails to properly filter or encode user-supplied data containing special characters or commands that can be interpreted in a different context, such as a command shell, file system, or data format.
Special Element Injection happens when user input containing control characters, escape sequences, or command delimiters is passed directly to a system component without proper validation. This allows attackers to inject instructions that are executed in a different 'plane' or context than intended—like tricking a log parser to run system commands or manipulating a configuration file reader to access sensitive data. The core issue is a failure to distinguish between pure data and executable instructions when handling external input. To prevent this, developers must implement strict input validation and context-aware output encoding. Always treat all user input as untrusted and sanitize it based on the specific context where it will be used—whether that's a shell command, a file path, a log entry, or a configuration syntax. Use allow-list validation for expected patterns and dedicated encoding libraries rather than attempting to create custom blacklists of 'bad' characters, which are often incomplete and easy to bypass.
Real-world impact

Real-world CVEs caused by CWE-75

No public CVE references are linked to this CWE in MITRE's catalog yet.

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-75

  • Requirements Programming languages and supporting technologies might be chosen which are not subject to these issues.
  • Implementation Utilize an appropriate mix of allowlist and denylist parsing to filter special element syntax from all input.
Detection signals

How to detect CWE-75

SAST High

Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.

DAST Moderate

Run dynamic application security testing against the live endpoint.

Runtime Moderate

Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.

Code review Moderate

Code review: flag any new code that handles input from this surface without using the validated framework helpers.

Plexicus auto-fix

Plexicus auto-detects CWE-75 and opens a fix PR in under 60 seconds.

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Frequently asked questions

Frequently asked questions

What is CWE-75?

This vulnerability occurs when an application fails to properly filter or encode user-supplied data containing special characters or commands that can be interpreted in a different context, such as a command shell, file system, or data format.

How serious is CWE-75?

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-75?

MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.

How can I prevent CWE-75?

Programming languages and supporting technologies might be chosen which are not subject to these issues. Utilize an appropriate mix of allowlist and denylist parsing to filter special element syntax from all input.

How does Plexicus detect and fix CWE-75?

Plexicus's SAST engine matches the data-flow signature for CWE-75 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-75?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/75.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-75

CWE-74 Parent

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

This vulnerability occurs when an application uses untrusted external input to build a command, query, or data structure for another…

CWE-1236 Sibling

Improper Neutralization of Formula Elements in a CSV File

This vulnerability occurs when an application writes user-supplied data into a CSV file without properly sanitizing special characters.…

CWE-77 Sibling

Improper Neutralization of Special Elements used in a Command ('Command Injection')

This vulnerability occurs when an application builds a system command using untrusted user input without properly sanitizing it. An…

CWE-78 Sibling

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

OS Command Injection occurs when an application builds a system command using untrusted, external input without properly sanitizing it.…

CWE-79 Sibling

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

This vulnerability occurs when a web application fails to properly sanitize or encode user-supplied input before displaying it on a…

CWE-88 Sibling

Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

This vulnerability occurs when an application builds a command string for execution by another component, but fails to properly separate…

CWE-89 Sibling

Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

SQL Injection occurs when an application builds a database query using untrusted user input without properly sanitizing it. This allows an…

CWE-91 Sibling

XML Injection (aka Blind XPath Injection)

XML Injection occurs when an application fails to properly validate or escape user-controlled input before including it in XML documents…

CWE-917 Sibling

Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')

Expression Language Injection occurs when an application uses untrusted, external input to build an expression language statement—common…

Resources

Further reading

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