63
input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by
introducing dangerous inputs after they have been checked.
Observed Examples
Reference Description
CVE-2002-1987 Protection mechanism checks for "/.." but doesn't account for Windows-specific
"\.." allowing read of arbitrary files.
https://www.cve.org/CVERecord?id=CVE-2002-1987
CVE-2005-2142 Directory traversal vulnerability in FTP server allows remote authenticated
attackers to list arbitrary directories via a "\.." sequence in an LS command.
https://www.cve.org/CVERecord?id=CVE-2005-2142
MemberOf Relationships
This MemberOf relationships table shows additional CWE Catgeories 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 Page
MemberOf 981 SFP Secondary Cluster: Path Traversal 888 2409
MemberOf 1404 Comprehensive Categorization: File Handling 1400 2529
Taxonomy Mappings
Mapped Taxonomy Name Node ID Fit Mapped Node Name
PLOVER '\..\filename' ('leading dot dot
backslash')
Software Fault Patterns SFP16 Path Traversal
CWE-30: Path Traversal: '\dir\..\filename'
Weakness ID : 30
Structure : Simple
Abstraction : Variant
Description
The product uses external input to construct a pathname that should be within a restricted
directory, but it does not properly neutralize '\dir\..\filename' (leading backslash dot dot) sequences
that can resolve to a location that is outside of that directory.
Extended Description
This allows attackers to traverse the file system to access files or directories that are outside of the
restricted directory.
This is similar to CWE-26, except using "\" instead of "/". The '\dir\..\filename' manipulation is useful
for bypassing some path traversal protection schemes. Sometimes a program only checks for "..\"
at the beginning of the input, so a "\..\" can bypass that check.
Relationships
The table(s) below shows the weaknesses and high level categories that are related to this
weakness. These relationships are defined as ChildOf, ParentOf, MemberOr 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 may want to be explored.
Relevant to the view "Research Concepts" (CWE-1000)
Nature Type ID Name Page
ChildOf 23 Relative Path Traversal 46
CWE Version 4.14
CWE-30: Path Traversal: '\dir\..\filename'
CWE-30: Path Traversal: '\dir\..\filename'