CWE-463 Base Incomplete

Deletion of Data Structure Sentinel

This vulnerability occurs when a program accidentally removes or corrupts a special marker used to define the boundaries of a data structure, leading to logic errors and unexpected behavior.

Definition

What is CWE-463?

This vulnerability occurs when a program accidentally removes or corrupts a special marker used to define the boundaries of a data structure, leading to logic errors and unexpected behavior.
Data structures often use hidden markers, called sentinels, to signal where they begin or end. Common examples include the null terminator ('\0') at the end of a string or a special node marking the tail of a linked list. If your code mistakenly deletes or overwrites this sentinel, the structure loses its defined boundary, causing functions that rely on it to fail or behave unpredictably. To prevent this, you should encapsulate the data structure and its sentinel within a controlled interface or API. This wrapper manages all access, ensuring that the critical sentinel value cannot be directly modified or deleted by other parts of the program. Treating the sentinel as protected internal state, rather than exposed data, is key to maintaining structural integrity and avoiding logic flaws.
Real-world impact

Real-world CVEs caused by CWE-463

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 C

This example creates a null terminated string and prints it contents.

Vulnerable C 
char *foo;
  int counter;
  foo=calloc(sizeof(char)*10);
  for (counter=0;counter!=10;counter++) {
  	foo[counter]='a';
  printf("%s\n",foo);
  }
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-463

  • Architecture and Design Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Build and Compilation Run or compile the software using features or extensions that automatically provide a protection mechanism that mitigates or eliminates buffer overflows. For example, certain compilers and extensions provide automatic buffer overflow detection mechanisms that are built into the compiled code. Examples include the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice.
  • Operation Use OS-level preventative functionality. Not a complete solution.
Detection signals

How to detect CWE-463

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-463 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.

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Frequently asked questions

Frequently asked questions

What is CWE-463?

This vulnerability occurs when a program accidentally removes or corrupts a special marker used to define the boundaries of a data structure, leading to logic errors and unexpected behavior.

How serious is CWE-463?

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-463?

MITRE lists the following affected platforms: C, C++.

How can I prevent CWE-463?

Use an abstraction library to abstract away risky APIs. Not a complete solution. Run or compile the software using features or extensions that automatically provide a protection mechanism that mitigates or eliminates buffer overflows. For example, certain compilers and extensions provide automatic buffer overflow detection mechanisms that are built into the compiled code. Examples include the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice.

How does Plexicus detect and fix CWE-463?

Plexicus's SAST engine matches the data-flow signature for CWE-463 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-463?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/463.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-463

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CWE-116 Sibling

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CWE-1426 Sibling

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CWE-170 Sibling

Improper Null Termination

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CWE-172 Sibling

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CWE-182 Sibling

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CWE-20 Sibling

Improper Input Validation

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CWE-228 Sibling

Improper Handling of Syntactically Invalid Structure

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Resources

Further reading

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