名前: Signed to Unsigned Conversion Error

The product uses a signed primitive and performs a cast to an unsigned primitive, which can produce an unexpected value if the value of the signed primitive can not be represented using an unsigned primitive.

一般情報

導入モード

Implementation : It is dangerous to rely on implicit casts between signed and unsigned numbers because the result can take on an unexpected value and violate assumptions made by the program.

適用可能なプラットフォーム

言語

名前： C (Undetermined)
名前： C++ (Undetermined)

一般的な結果

スコープ	影響	可能性
Integrity	Unexpected State, Modify Memory, Read Memory 注記：Conversion between signed and unsigned values can lead to a variety of errors, but from a security standpoint is most commonly associated with integer overflow and buffer overflow vulnerabilities. Often, functions will return negative values to indicate a failure. When the result of a function is to be used as a size parameter, using these negative return values can have unexpected results. For example, if negative size values are passed to the standard memory copy or allocation functions, they will be implicitly cast to a large unsigned value. This may lead to an exploitable buffer overflow or underflow condition.

観察された例

参考文献	説明
CVE-2025-27363	Font rendering library does not properly handle assigning a signed short value to an unsigned long (CWE-195), leading to an integer wraparound (CWE-190), causing too small of a buffer (CWE-131), leading to an out-of-bounds write (CWE-787).
CVE-2007-4268	Chain: integer signedness error (CWE-195) passes signed comparison, leading to heap overflow (CWE-122)

検出方法

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.)
有効性 : High

脆弱性マッピングノート

理由 : This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
コメント : 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.

参考文献

REF-62

The Art of Software Security Assessment
Mark Dowd, John McDonald, Justin Schuh.

REF-18

The CLASP Application Security Process
Secure Software, Inc..
https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf

REF-1534

Automated Technical Debt Measure, Version 2
OMG.
https://www.omg.org/spec/ATDM2/1.0/PDF

登録情報

名前	組織	日付	リリース日	Version
CLASP		2006-07-19 +00:00	2006-07-19 +00:00	Draft 3

変更履歴

名前	組織	日付	コメント
CWE Content Team	MITRE	2008-09-08 +00:00	updated Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
CWE Content Team	MITRE	2009-05-27 +00:00	updated Demonstrative_Examples
CWE Content Team	MITRE	2009-10-29 +00:00	updated Common_Consequences, Description, Other_Notes, Relationships
CWE Content Team	MITRE	2010-02-16 +00:00	updated Demonstrative_Examples
CWE Content Team	MITRE	2010-04-05 +00:00	updated Demonstrative_Examples
CWE Content Team	MITRE	2011-03-29 +00:00	updated Relationships
CWE Content Team	MITRE	2011-06-01 +00:00	updated Common_Consequences
CWE Content Team	MITRE	2011-06-27 +00:00	updated Common_Consequences
CWE Content Team	MITRE	2012-05-11 +00:00	updated Demonstrative_Examples, References, Relationships
CWE Content Team	MITRE	2014-06-23 +00:00	updated Demonstrative_Examples, Description
CWE Content Team	MITRE	2014-07-30 +00:00	updated Relationships, Taxonomy_Mappings
CWE Content Team	MITRE	2017-01-19 +00:00	updated Relationships
CWE Content Team	MITRE	2017-11-08 +00:00	updated Observed_Examples, Taxonomy_Mappings
CWE Content Team	MITRE	2019-01-03 +00:00	updated Relationships
CWE Content Team	MITRE	2020-02-24 +00:00	updated Relationships
CWE Content Team	MITRE	2020-08-20 +00:00	updated Relationships
CWE Content Team	MITRE	2020-12-10 +00:00	updated Relationships
CWE Content Team	MITRE	2021-03-15 +00:00	updated Demonstrative_Examples, References
CWE Content Team	MITRE	2023-01-31 +00:00	updated Description
CWE Content Team	MITRE	2023-04-27 +00:00	updated Detection_Factors, Relationships
CWE Content Team	MITRE	2023-06-29 +00:00	updated Mapping_Notes
CWE Content Team	MITRE	2025-04-03 +00:00	updated Observed_Examples
CWE Content Team	MITRE	2025-12-11 +00:00	updated Weakness_Ordinalities
CWE Content Team	MITRE	2026-10-28 +00:00	updated Common_Consequences, Demonstrative_Examples, Description, Modes_of_Introduction, References

CWE-195 詳細

CWE-195