The product does not properly handle special paths that may identify the data or resource fork of a file on the HFS+ file system.
If the product chooses actions to take based on the file name, then if an attacker provides the data or resource fork, the product may take unexpected actions. Further, if the product intends to restrict access to a file, then an attacker might still be able to bypass intended access restrictions by requesting the data or resource fork for that file.

Resultant

The Apple HFS+ file system permits files to have multiple data input streams, accessible through special paths. The Mac OS X operating system provides a way to access the different data input streams through special paths and as an extended attribute:

- Resource fork: file/..namedfork/rsrc, file/rsrc (deprecated), xattr:com.apple.ResourceFork
- Data fork: file/..namedfork/data (only versions prior to Mac OS X v10.5)

Additionally, on filesystems that lack native support for multiple streams, the resource fork and file metadata may be stored in a file with "._" prepended to the name.
Forks can also be accessed through non-portable APIs.
Forks inherit the file system access controls of the file they belong to.
Programs need to control access to these paths, if the processing of a file system object is dependent on the structure of its path.

Implementation

Confidentiality
Integrity
Read Files or Directories
Modify Files or Directories

Consider a web server that uses the Apple
HFS+ file system. It interprets FILE.cgi as processing
instructions.
An adversary could request
"FILE.cgi/..namedfork/data" to prevent FILE.cgi from
being executed, instead disclosing the source code for
FILE.cgi. This might occur because the web server
invokes the default handler which may return the
contents of the file.

CVE-2004-1084
Server allows remote attackers to read files and resource fork content via HTTP requests to certain special file names related to multiple data streams in HFS+.
https://www.cve.org/CVERecord?id=CVE-2004-1084

File Processing

File or Directory

Allowed
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.
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.

This and similar problems exist because the same resource can have multiple identifiers that dictate which behavior can be performed on the resource.
Under-studied

PLOVER
2006-07-19
Draft 3
2006-07-19

Eric Dalci
Cigital
2008-07-01
updated Time_of_Introduction

CWE Content Team
MITRE
2008-09-08
updated Relationships, Other_Notes, Taxonomy_Mappings

David Remahl
Apple
2008-11-05
clarified description, provided background details, and added demonstrative example

CWE Content Team
MITRE
2008-11-24
updated Applicable_Platforms, Background_Details, Demonstrative_Examples, Description, Name, References

CWE Content Team
MITRE
2009-05-27
updated Name

CWE Content Team
MITRE
2009-10-29
updated Other_Notes, Theoretical_Notes

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences

CWE Content Team
MITRE
2012-05-11
updated Observed_Examples, Relationships

CWE Content Team
MITRE
2014-07-30
updated Relationships

CWE Content Team
MITRE
2017-11-08
updated Applicable_Platforms, References, Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2020-02-24
updated Relationships

CWE Content Team
MITRE
2023-01-31
updated Description

CWE Content Team
MITRE
2023-04-27
updated References, Relationships, Time_of_Introduction

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2025-09-09
4.18
2025-09-09
updated Affected_Resources, Functional_Areas

CWE Content Team
MITRE
2025-12-11
4.19
2025-12-11
updated Demonstrative_Examples, Weakness_Ordinalities

Apple HFS+ Alternate Data Stream
Failure to Handle Apple HFS+ Alternate Data Stream Path