Détail du CWE-783

CWE-783

Operator Precedence Logic Error
Bas
Draft
2009-07-27
00h00 +00:00
2025-12-11
00h00 +00:00
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Nom: Operator Precedence Logic Error

The product uses an expression in which operator precedence causes incorrect logic to be used.

Description du CWE

While often just a bug, operator precedence logic errors can have serious consequences if they are used in security-critical code, such as making an authentication decision.

Informations générales

Modes d'introduction

Implementation : Logic errors related to operator precedence may cause problems even during normal operation, so they are probably discovered quickly during the testing phase. If testing is incomplete or there is a strong reliance on manual review of the code, then these errors may not be discovered before the software is deployed.

Plateformes applicables

Langue

Name: C (Rarely)
Name: C++ (Rarely)
Class: Not Language-Specific (Rarely)

Conséquences courantes

Portée Impact Probabilité
Confidentiality
Integrity
Availability
Varies by Context, Unexpected State

Note: The consequences will vary based on the context surrounding the incorrect precedence. In a security decision, integrity or confidentiality are the most likely results. Otherwise, a crash may occur due to the software reaching an unexpected state.

Exemples observés

Références Description

CVE-2008-2516

Authentication module allows authentication bypass because it uses "(x = call(args) == SUCCESS)" instead of "((x = call(args)) == SUCCESS)".

CVE-2008-0599

Chain: Language interpreter calculates wrong buffer size (CWE-131) by using "size = ptr ? X : Y" instead of "size = (ptr ? X : Y)" expression.

CVE-2001-1155

Chain: product does not properly check the result of a reverse DNS lookup because of operator precedence (CWE-783), allowing bypass of DNS-based access restrictions.

Mesures d’atténuation potentielles

Phases : Implementation
Regularly wrap sub-expressions in parentheses, especially in security-critical code.

Méthodes de détection

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.)
Efficacité : High

Notes de cartographie des vulnérabilités

Justification : 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.
Commentaire : 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.

Références

REF-704

EXP00-C. Use parentheses for precedence of operation
CERT.
https://www.securecoding.cert.org/confluence/display/seccode/EXP00-C.+Use+parentheses+for+precedence+of+operation

REF-62

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

Soumission

Nom Organisation Date Date de publication Version
CWE Content Team MITRE 2009-07-16 +00:00 2009-07-27 +00:00 1.5

Modifications

Nom Organisation Date Commentaire
CWE Content Team MITRE 2009-12-28 +00:00 updated Observed_Examples
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 2017-11-08 +00:00 updated Taxonomy_Mappings, Time_of_Introduction
CWE Content Team MITRE 2019-01-03 +00:00 updated Taxonomy_Mappings
CWE Content Team MITRE 2019-06-20 +00:00 updated Type
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 2021-03-15 +00:00 updated Relationships
CWE Content Team MITRE 2023-01-31 +00:00 updated Description
CWE Content Team MITRE 2023-04-27 +00:00 updated Relationships
CWE Content Team MITRE 2023-06-29 +00:00 updated Mapping_Notes
CWE Content Team MITRE 2025-12-11 +00:00 updated Detection_Factors, Weakness_Ordinalities