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Home > CWE List > CWE-197: Numeric Truncation Error (4.20)  
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    CWE-197: Numeric Truncation Error

    Weakness ID: 197
    Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
    Abstraction: Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
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    + Description
    Truncation errors occur when a primitive is cast to a primitive of a smaller size and data is lost in the conversion.
    + Extended Description
    When a primitive is cast to a smaller primitive, the high order bits of the large value are lost in the conversion, potentially resulting in an unexpected value that is not equal to the original value. This value may be required as an index into a buffer, a loop iterator, or simply necessary state data. In any case, the value cannot be trusted and the system will be in an undefined state. While this method may be employed viably to isolate the low bits of a value, this usage is rare, and truncation usually implies that an implementation error has occurred.
    + Common Consequences
    Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
    Impact Details

    Modify Memory

    		Scope: Integrity

    The true value of the data is lost and corrupted data is used.
    + Potential Mitigations
    Phase(s) Mitigation

    Implementation
    Ensure that no casts, implicit or explicit, take place that move from a larger size primitive or a smaller size primitive.
    + Relationships
    Section Help This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
    + Relevant to the view "Research Concepts" (View-1000)
    Nature Type ID Name
    ChildOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 681 Incorrect Conversion between Numeric Types
    CanAlsoBe Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource. 192 Integer Coercion Error
    CanAlsoBe Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource. 194 Unexpected Sign Extension
    CanAlsoBe Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource. 195 Signed to Unsigned Conversion Error
    CanAlsoBe Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource. 196 Unsigned to Signed Conversion Error
    + Relevant to the view "CISQ Quality Measures (2020)" (View-1305)
    Nature Type ID Name
    ChildOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 681 Incorrect Conversion between Numeric Types
    + Relevant to the view "CISQ Data Protection Measures" (View-1340)
    Nature Type ID Name
    ChildOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 681 Incorrect Conversion between Numeric Types
    + Modes Of Introduction
    Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
    Phase Note
    Implementation
    + Applicable Platforms
    Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.
    Languages

    C (Undetermined Prevalence)

    C++ (Undetermined Prevalence)

    Java (Undetermined Prevalence)

    C# (Undetermined Prevalence)

    + Likelihood Of Exploit
    Low
    + Demonstrative Examples

    Example 1


    This example, while not exploitable, shows the possible mangling of values associated with truncation errors:

    (bad code)
    Example Language: C 
    int intPrimitive;
    short shortPrimitive;
    intPrimitive = (int)(~((int)0) ^ (1 << (sizeof(int)*8-1)));
    shortPrimitive = intPrimitive;
    printf("Int MAXINT: %d\nShort MAXINT: %d\n", intPrimitive, shortPrimitive);

    The above code, when compiled and run on certain systems, returns the following output:

    (result)
     
    Int MAXINT: 2147483647
    Short MAXINT: -1

    This problem may be exploitable when the truncated value is used as an array index, which can happen implicitly when 64-bit values are used as indexes, as they are truncated to 32 bits.



    Example 2


    In the following Java example, the method updateSalesForProduct is part of a business application class that updates the sales information for a particular product. The method receives as arguments the product ID and the integer amount sold. The product ID is used to retrieve the total product count from an inventory object which returns the count as an integer. Before calling the method of the sales object to update the sales count the integer values are converted to The primitive type short since the method requires short type for the method arguments.

    (bad code)
    Example Language: Java 
    ...
    // update sales database for number of product sold with product ID
    public void updateSalesForProduct(String productID, int amountSold) {

    // get the total number of products in inventory database
    int productCount = inventory.getProductCount(productID);
    // convert integer values to short, the method for the

    // sales object requires the parameters to be of type short
    short count = (short) productCount;
    short sold = (short) amountSold;
    // update sales database for product
    sales.updateSalesCount(productID, count, sold);
    }
    ...

    However, a numeric truncation error can occur if the integer values are higher than the maximum value allowed for the primitive type short. This can cause unexpected results or loss or corruption of data. In this case the sales database may be corrupted with incorrect data. Explicit casting from a from a larger size primitive type to a smaller size primitive type should be prevented. The following example an if statement is added to validate that the integer values less than the maximum value for the primitive type short before the explicit cast and the call to the sales method.

    (good code)
    Example Language: Java 
    ...
    // update sales database for number of product sold with product ID
    public void updateSalesForProduct(String productID, int amountSold) {

    // get the total number of products in inventory database
    int productCount = inventory.getProductCount(productID);
    // make sure that integer numbers are not greater than

    // maximum value for type short before converting
    if ((productCount < Short.MAX_VALUE) && (amountSold < Short.MAX_VALUE)) {

    // convert integer values to short, the method for the

    // sales object requires the parameters to be of type short
    short count = (short) productCount;
    short sold = (short) amountSold;
    // update sales database for product
    sales.updateSalesCount(productID, count, sold);

    else {
    // throw exception or perform other processing
    ...
    }
    }
    ...


    + Selected Observed Examples

    Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.

    Reference Description
    Chain: integer truncation (CWE-197) causes small buffer allocation (CWE-131) leading to out-of-bounds write (CWE-787) in kernel pool, as exploited in the wild per CISA KEV.
    Integer truncation of length value leads to heap-based buffer overflow.
    Size of a particular type changes for 64-bit platforms, leading to an integer truncation in document processor causes incorrect index to be generated.
    + Weakness Ordinalities
    Ordinality Description
    Primary
    (where the weakness exists independent of other weaknesses)
    Resultant
    (where the weakness is typically related to the presence of some other weaknesses)
    + Detection Methods
    Method Details

    Fuzzing
    Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.

    Effectiveness: High

    Automated Static Analysis
    Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

    Effectiveness: High
    + Memberships
    Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
    Nature Type ID Name
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 738 CERT C Secure Coding Standard (2008) Chapter 5 - Integers (INT)
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 848 The CERT Oracle Secure Coding Standard for Java (2011) Chapter 5 - Numeric Types and Operations (NUM)
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 872 CERT C++ Secure Coding Section 04 - Integers (INT)
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 998 SFP Secondary Cluster: Glitch in Computation
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1137 SEI CERT Oracle Secure Coding Standard for Java - Guidelines 03. Numeric Types and Operations (NUM)
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1158 SEI CERT C Coding Standard - Guidelines 04. Integers (INT)
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1159 SEI CERT C Coding Standard - Guidelines 05. Floating Point (FLP)
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1163 SEI CERT C Coding Standard - Guidelines 09. Input Output (FIO)
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1416 Comprehensive Categorization: Resource Lifecycle Management
    + Vulnerability Mapping Notes
    Usage ALLOWED
    (this CWE ID may be used to map to real-world vulnerabilities)
    Reason Acceptable-Use

    Rationale

    		This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

    Comments

    		Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
    + Notes

    Research Gap

    This weakness has traditionally been under-studied and under-reported, although vulnerabilities in popular software have been published in 2008 and 2009.
    + Taxonomy Mappings
    Mapped Taxonomy Name Node ID Fit Mapped Node Name
    PLOVER Numeric truncation error
    CLASP Truncation error
    CERT C Secure Coding FIO34-C CWE More Abstract Distinguish between characters read from a file and EOF or WEOF
    CERT C Secure Coding FLP34-C CWE More Abstract Ensure that floating point conversions are within range of the new type
    CERT C Secure Coding INT02-C Understand integer conversion rules
    CERT C Secure Coding INT05-C Do not use input functions to convert character data if they cannot handle all possible inputs
    CERT C Secure Coding INT31-C CWE More Abstract Ensure that integer conversions do not result in lost or misinterpreted data
    The CERT Oracle Secure Coding Standard for Java (2011) NUM12-J Ensure conversions of numeric types to narrower types do not result in lost or misinterpreted data
    Software Fault Patterns SFP1 Glitch in computation
    + References
    [REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 6, "Truncation", Page 259. 1st Edition. Addison Wesley. 2006.
    + Content History
    + Submissions
    Submission Date Submitter Organization
    2006-07-19
    (CWE Draft 3, 2006-07-19)     		PLOVER
    + Modifications
    Modification Date Modifier Organization
    2025-12-11
    (CWE 4.19, 2025-12-11)     		CWE Content Team MITRE
    updated Weakness_Ordinalities
    2023-06-29
    (CWE 4.12, 2023-06-29)     		CWE Content Team MITRE
    updated Mapping_Notes
    2023-04-27
    (CWE 4.11, 2023-04-27)     		CWE Content Team MITRE
    updated Detection_Factors, Relationships
    2022-06-28
    (CWE 4.8, 2022-06-28)     		CWE Content Team MITRE
    updated Observed_Examples
    2020-12-10
    (CWE 4.3, 2020-12-10)     		CWE Content Team MITRE
    updated Relationships
    2020-08-20
    (CWE 4.2, 2020-08-20)     		CWE Content Team MITRE
    updated Relationships
    2020-02-24
    (CWE 4.0, 2020-02-24)     		CWE Content Team MITRE
    updated Relationships
    2019-01-03
    (CWE 3.2, 2019-01-03)     		CWE Content Team MITRE
    updated Relationships, Taxonomy_Mappings
    2017-11-08
    (CWE 3.0, 2017-11-08)     		CWE Content Team MITRE
    updated Taxonomy_Mappings
    2014-07-30
    (CWE 2.8, 2014-07-31)     		CWE Content Team MITRE
    updated Relationships, Taxonomy_Mappings
    2012-05-11
    (CWE 2.2, 2012-05-15)     		CWE Content Team MITRE
    updated References, Relationships, Taxonomy_Mappings
    2011-09-13
    (CWE 2.1, 2011-09-13)     		CWE Content Team MITRE
    updated Relationships, Taxonomy_Mappings
    2011-06-01
    (CWE 1.13, 2011-06-01)     		CWE Content Team MITRE
    updated Common_Consequences, Relationships, Taxonomy_Mappings
    2010-12-13
    (CWE 1.11, 2010-12-13)     		CWE Content Team MITRE
    updated Demonstrative_Examples
    2009-07-27
    (CWE 1.5, 2009-07-27)     		CWE Content Team MITRE
    updated Description, Observed_Examples, Other_Notes, Research_Gaps
    2009-05-27
    (CWE 1.4, 2009-05-27)     		CWE Content Team MITRE
    updated Demonstrative_Examples
    2008-11-24
    (CWE 1.1, 2008-11-25)     		CWE Content Team MITRE
    updated Relationships, Taxonomy_Mappings
    2008-09-08
    (CWE 1.0, 2008-09-09)     		CWE Content Team MITRE
    updated Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
    Page Last Updated: April 30, 2026
     

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