CWE-174
Double Decoding of the Same Data
Draft
2006-07-19
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2025-12-11
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Notifications pour un CWE
Restez informé de toutes modifications pour un CWE spécifique.
Nom: Double Decoding of the Same Data
The product decodes the same input twice, which can limit the effectiveness of any protection mechanism that occurs in between the decoding operations.
Informations générales
Modes d'introduction
ImplementationPlateformes applicables
Langue
Class: Not Language-Specific (Undetermined)Conséquences courantes
| Portée | Impact | Probabilité |
|---|---|---|
| Access Control Confidentiality Availability Integrity Other | Bypass Protection Mechanism, Execute Unauthorized Code or Commands, Varies by Context |
Exemples observés
| Références | Description |
|---|---|
CVE-2004-1315 | Forum software improperly URL decodes the highlight parameter when extracting text to highlight, which allows remote attackers to execute arbitrary PHP code by double-encoding the highlight value so that special characters are inserted into the result. |
CVE-2004-1939 | XSS protection mechanism attempts to remove "/" that could be used to close tags, but it can be bypassed using double encoded slashes (%252F) |
CVE-2001-0333 | Directory traversal using double encoding. |
CVE-2004-1938 | "%2527" (double-encoded single quote) used in SQL injection. |
CVE-2005-1945 | Double hex-encoded data. |
CVE-2005-0054 | Browser executes HTML at higher privileges via URL with hostnames that are double hex encoded, which are decoded twice to generate a malicious hostname. |
Mesures d’atténuation potentielles
Phases : Architecture and DesignAvoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
Phases : Implementation
Phases : Implementation
Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
Phases : Implementation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
Notes de cartographie des vulnérabilités
Justification : 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.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.
Notes
Probably under-studied.Soumission
| Nom | Organisation | Date | Date de publication | Version |
|---|---|---|---|---|
| PLOVER | Draft 3 |
Modifications
| Nom | Organisation | Date | Commentaire |
|---|---|---|---|
| Eric Dalci | Cigital | updated Potential_Mitigations | |
| CWE Content Team | MITRE | updated Relationships, Observed_Example, Taxonomy_Mappings | |
| CWE Content Team | MITRE | updated Observed_Examples | |
| CWE Content Team | MITRE | updated Potential_Mitigations | |
| CWE Content Team | MITRE | updated Potential_Mitigations | |
| CWE Content Team | MITRE | updated Common_Consequences | |
| CWE Content Team | MITRE | updated Common_Consequences, Observed_Examples, Relationships | |
| CWE Content Team | MITRE | updated Potential_Mitigations | |
| CWE Content Team | MITRE | updated Relationships | |
| CWE Content Team | MITRE | updated Applicable_Platforms | |
| CWE Content Team | MITRE | updated Potential_Mitigations, Relationships | |
| CWE Content Team | MITRE | updated Potential_Mitigations | |
| CWE Content Team | MITRE | updated Description | |
| CWE Content Team | MITRE | updated Relationships | |
| CWE Content Team | MITRE | updated Mapping_Notes | |
| CWE Content Team | MITRE | updated Weakness_Ordinalities |
