CWE-464: Addition of Data Structure Sentinel

Extended Description

Data-structure sentinels are often used to mark the structure of data. A common example of this is the null character at the end of strings or a special sentinel to mark the end of a linked list. It is dangerous to allow this type of control data to be easily accessible. Therefore, it is important to protect from the addition or modification of sentinels.

Code Examples & CVEs

Demonstrative Examples

The following example assigns some character values to a list of characters and prints them each individually, and then as a string. The third character value is intended to be an integer taken from user input and converted to an int. The first print statement will print each character separated by a space.

However, if a NULL byte is read from stdin by fgetc, then it will return 0. When foo is printed as a string, the 0 at character foo[2] will act as a NULL terminator, and the second printf() statement will not print foo[3].

BadC

char *foo; 				   foo=malloc(sizeof(char)*5); 				   foo[0]='a'; 				   foo[1]='a'; 				   foo[2]=fgetc(stdin); 				   foo[3]='c'; 				   foo[4]='\0'; 				   printf("%c %c %c %c %c \n",foo[0],foo[1],foo[2],foo[3],foo[4]); 				   printf("%s\n",foo);

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-464 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-464, Addition of Data Structure Sentinel, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

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

Address Addition of Data Structure Sentinel during Implementation

MITRE associates mitigation with Implementation, Architecture and Design, and Operation; recorded impacts include Modify Application Data; related weaknesses include CWE-138. Use these source-defined anchors to turn CWE-464 into implementation, review, and verification checks for the affected component.

CWE-464: Addition of Data Structure Sentinel — MITRE CWE

Triage CWE-464 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-464, Addition of Data Structure Sentinel, 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-464

Apply MITRE's full root-cause mapping guidance when using CWE-464, Addition of Data Structure Sentinel. 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-464 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-464, Addition of Data Structure Sentinel. 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-464: Addition of Data Structure Sentinel?+

CWE-464: Addition of Data Structure Sentinel is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The accidental addition of a data-structure sentinel can cause serious programming logic problems. Data-structure sentinels are often used to mark the structure of data. A common example of this is the null character at the end of strings or a special sentinel to mark the end of a linked list. It is dangerous to allow this type of control data to be easily accessible. Therefore, it is important to protect from the addition or modification of sentinels.

What are the security consequences of Addition of Data Structure Sentinel?+

If exploited, CWE-464 (Addition of Data Structure Sentinel) it can compromise Integrity, leading to outcomes such as Modify Application Data.

How do you prevent or mitigate Addition of Data Structure Sentinel?+

Recommended mitigations for CWE-464 include: Encapsulate the user from interacting with data sentinels. Validate user input to verify that sentinels are not present. Proper error checking can reduce the risk of inadvertently introducing sentinel values into data. For example, if a parsing function fails or encounters an error, it might return a value that is the same as the sentinel. Use an abstraction library to abstract away risky APIs. This is not a complete solution.

Which programming languages are affected by Addition of Data Structure Sentinel?+

CWE-464 commonly affects C and C++. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-464 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-464: Addition of Data Structure Sentinel

Extended Description

Technical Details

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Code Examples & CVEs

Demonstrative Examples

CWE Relationships

Parent Weaknesses

Source-backed guidance

Verify controls for CWE-464 with SSDF evidence

Address Addition of Data Structure Sentinel during Implementation

Triage CWE-464 against known exploitation evidence

Apply precise root-cause mapping to CWE-464

Validate CWE-464 with root-cause mapping checks

Frequently Asked Questions

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