The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory.

Primary

Resultant

Zip Slip
"Zip slip" is an attack that uses file archives (e.g., ZIP, tar, rar, etc.) that contain filenames with path traversal sequences that cause the files to be written outside of the directory under which the archive is expected to be extracted [REF-1282]. It is most commonly used for relative path traversal (CWE-23) and link following (CWE-59).

Implementation

Integrity
Confidentiality
Availability
Execute Unauthorized Code or Commands
The attacker may be able to create or overwrite critical files that are used to execute code, such as programs or libraries.

Integrity
Modify Files or Directories
The attacker may be able to overwrite or create critical files, such as programs, libraries, or important data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, appending a new account at the end of a password file may allow an attacker to bypass authentication.

Confidentiality
Read Files or Directories
The attacker may be able read the contents of unexpected files and expose sensitive data by traversing the file system to access files or directories that are outside of the restricted directory. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, by reading a password file, the attacker could conduct brute force password guessing attacks in order to break into an account on the system.

Availability
DoS: Crash, Exit, or Restart
The attacker may be able to overwrite, delete, or corrupt unexpected critical files such as programs, libraries, or important data. This may prevent the product from working at all and in the case of a protection mechanisms such as authentication, it has the potential to lockout every user of the product.

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.)
High

Implementation
Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.

Implementation
Input Validation

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.
Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes:

realpath() in C
getCanonicalPath() in Java
GetFullPath() in ASP.NET
realpath() or abs_path() in Perl
realpath() in PHP

Operation
Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Moderate
An application firewall might not cover all possible input vectors. In addition, attack techniques might be available to bypass the protection mechanism, such as using malformed inputs that can still be processed by the component that receives those inputs. Depending on functionality, an application firewall might inadvertently reject or modify legitimate requests. Finally, some manual effort may be required for customization.

The following URLs are vulnerable to this attack:

http://example.com/get-files.jsp?file=report.pdfhttp://example.com/get-page.php?home=aaa.htmlhttp://example.com/some-page.asp?page=index.html

A simple way to execute this attack is like this:

http://example.com/get-files?file=../../../../somedir/somefilehttp://example.com/../../../../etc/shadowhttp://example.com/get-files?file=../../../../etc/passwd

The following code could be for a social networking application in which each user's profile information is stored in a separate file. All files are stored in a single directory.

my $dataPath = "/users/cwe/profiles";my $username = param("user");my $profilePath = $dataPath . "/" . $username;
open(my $fh, "<", $profilePath) || ExitError("profile read error: $profilePath");print "<ul>\n";while (<$fh>) {print "<li>$_</li>\n";}print "</ul>\n";

While the programmer intends to access files such as "/users/cwe/profiles/alice" or "/users/cwe/profiles/bob", there is no verification of the incoming user parameter. An attacker could provide a string such as:

../../../etc/passwd

The program would generate a profile pathname like this:

/users/cwe/profiles/../../../etc/passwd

When the file is opened, the operating system resolves the "../" during path canonicalization and actually accesses this file:

/etc/passwd

As a result, the attacker could read the entire text of the password file.
Notice how this code also contains an error message information leak (CWE-209) if the user parameter does not produce a file that exists: the full pathname is provided. Because of the lack of output encoding of the file that is retrieved, there might also be a cross-site scripting problem (CWE-79) if profile contains any HTML, but other code would need to be examined.

The following code demonstrates the unrestricted upload of a file with a Java servlet and a path traversal vulnerability. The action attribute of an HTML form is sending the upload file request to the Java servlet.

<form action="FileUploadServlet" method="post" enctype="multipart/form-data">
Choose a file to upload:<input type="file" name="filename"/><br/><input type="submit" name="submit" value="Submit"/>
</form>

When submitted the Java servlet's doPost method will receive the request, extract the name of the file from the Http request header, read the file contents from the request and output the file to the local upload directory.

public class FileUploadServlet extends HttpServlet {

...
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

response.setContentType("text/html");PrintWriter out = response.getWriter();String contentType = request.getContentType();
// the starting position of the boundary headerint ind = contentType.indexOf("boundary=");String boundary = contentType.substring(ind+9);
String pLine = new String();String uploadLocation = new String(UPLOAD_DIRECTORY_STRING); //Constant value
// verify that content type is multipart form dataif (contentType != null && contentType.indexOf("multipart/form-data") != -1) {

// extract the filename from the Http headerBufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));...pLine = br.readLine();String filename = pLine.substring(pLine.lastIndexOf("\\"), pLine.lastIndexOf("\""));...
// output the file to the local upload directorytry {
BufferedWriter bw = new BufferedWriter(new FileWriter(uploadLocation+filename, true));for (String line; (line=br.readLine())!=null; ) {if (line.indexOf(boundary) == -1) {bw.write(line);bw.newLine();bw.flush();}} //end of for loopbw.close();

} catch (IOException ex) {...}// output successful upload response HTML page
}// output unsuccessful upload response HTML pageelse{...}
}...

}

This code does not perform a check on the type of the file being uploaded (CWE-434). This could allow an attacker to upload any executable file or other file with malicious code.
Additionally, the creation of the BufferedWriter object is subject to relative path traversal (CWE-23). Since the code does not check the filename that is provided in the header, an attacker can use "../" sequences to write to files outside of the intended directory. Depending on the executing environment, the attacker may be able to specify arbitrary files to write to, leading to a wide variety of consequences, from code execution, XSS (CWE-79), or system crash.

CVE-2024-37032
Large language model (LLM) management tool does not
validate the format of a digest value (CWE-1287) from a
private, untrusted model registry, enabling relative
path traversal (CWE-23), a.k.a. Probllama
https://www.cve.org/CVERecord?id=CVE-2024-37032

CVE-2024-0520
Product for managing datasets for AI model training and evaluation allows both relative (CWE-23) and absolute (CWE-36) path traversal to overwrite files via the Content-Disposition header
https://www.cve.org/CVERecord?id=CVE-2024-0520

CVE-2022-45918
Chain: a learning management tool debugger uses external input to locate previous session logs (CWE-73) and does not properly validate the given path (CWE-20), allowing for filesystem path traversal using "../" sequences (CWE-24)
https://www.cve.org/CVERecord?id=CVE-2022-45918

CVE-2019-20916
Python package manager does not correctly restrict the filename specified in a Content-Disposition header, allowing arbitrary file read using path traversal sequences such as "../"
https://www.cve.org/CVERecord?id=CVE-2019-20916

CVE-2022-24877
directory traversal in Go-based Kubernetes operator app allows accessing data from the controller's pod file system via ../ sequences in a yaml file
https://www.cve.org/CVERecord?id=CVE-2022-24877

CVE-2020-4053
a Kubernetes package manager written in Go allows malicious plugins to inject path traversal sequences into a plugin archive ("Zip slip") to copy a file outside the intended directory
https://www.cve.org/CVERecord?id=CVE-2020-4053

CVE-2021-21972
Chain: Cloud computing virtualization platform does not require authentication for upload of a tar format file (CWE-306), then uses .. path traversal sequences (CWE-23) in the file to access unexpected files, as exploited in the wild per CISA KEV.
https://www.cve.org/CVERecord?id=CVE-2021-21972

CVE-2019-10743
Go-based archive library allows extraction of files to locations outside of the target folder with "../" path traversal sequences in filenames in a zip file, aka "Zip Slip"
https://www.cve.org/CVERecord?id=CVE-2019-10743

CVE-2002-0298
Server allows remote attackers to cause a denial of service via certain HTTP GET requests containing a %2e%2e (encoded dot-dot), several "/../" sequences, or several "../" in a URI.
https://www.cve.org/CVERecord?id=CVE-2002-0298

CVE-2002-0661
"\" not in denylist for web server, allowing path traversal attacks when the server is run in Windows and other OSes.
https://www.cve.org/CVERecord?id=CVE-2002-0661

CVE-2002-0946
Arbitrary files may be read files via ..\ (dot dot) sequences in an HTTP request.
https://www.cve.org/CVERecord?id=CVE-2002-0946

CVE-2002-1042
Directory traversal vulnerability in search engine for web server allows remote attackers to read arbitrary files via "..\" sequences in queries.
https://www.cve.org/CVERecord?id=CVE-2002-1042

CVE-2002-1209
Directory traversal vulnerability in FTP server allows remote attackers to read arbitrary files via "..\" sequences in a GET request.
https://www.cve.org/CVERecord?id=CVE-2002-1209

CVE-2002-1178
Directory traversal vulnerability in servlet allows remote attackers to execute arbitrary commands via "..\" sequences in an HTTP request.
https://www.cve.org/CVERecord?id=CVE-2002-1178

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

CVE-2002-0160
The administration function in Access Control Server allows remote attackers to read HTML, Java class, and image files outside the web root via a "..\.." sequence in the URL to port 2002.
https://www.cve.org/CVERecord?id=CVE-2002-0160

CVE-2001-0467
"\..." in web server
https://www.cve.org/CVERecord?id=CVE-2001-0467

CVE-2001-0963
"..." in cd command in FTP server
https://www.cve.org/CVERecord?id=CVE-2001-0963

CVE-2001-1193
"..." in cd command in FTP server
https://www.cve.org/CVERecord?id=CVE-2001-1193

CVE-2001-1131
"..." in cd command in FTP server
https://www.cve.org/CVERecord?id=CVE-2001-1131

CVE-2001-0480
read of arbitrary files and directories using GET or CD with "..." in Windows-based FTP server.
https://www.cve.org/CVERecord?id=CVE-2001-0480

CVE-2002-0288
read files using "." and Unicode-encoded "/" or "\" characters in the URL.
https://www.cve.org/CVERecord?id=CVE-2002-0288

CVE-2003-0313
Directory listing of web server using "..."
https://www.cve.org/CVERecord?id=CVE-2003-0313

CVE-2005-1658
Triple dot
https://www.cve.org/CVERecord?id=CVE-2005-1658

CVE-2000-0240
read files via "/........../" in URL
https://www.cve.org/CVERecord?id=CVE-2000-0240

CVE-2000-0773
read files via "...." in web server
https://www.cve.org/CVERecord?id=CVE-2000-0773

CVE-1999-1082
read files via "......" in web server (doubled triple dot?)
https://www.cve.org/CVERecord?id=CVE-1999-1082

CVE-2004-2121
read files via "......" in web server (doubled triple dot?)
https://www.cve.org/CVERecord?id=CVE-2004-2121

CVE-2001-0491
multiple attacks using "..", "...", and "...." in different commands
https://www.cve.org/CVERecord?id=CVE-2001-0491

CVE-2001-0615
"..." or "...." in chat server
https://www.cve.org/CVERecord?id=CVE-2001-0615

CVE-2005-2169
chain: ".../...//" bypasses protection mechanism using regexp's that remove "../" resulting in collapse into an unsafe value "../" (CWE-182) and resultant path traversal.
https://www.cve.org/CVERecord?id=CVE-2005-2169

CVE-2005-0202
".../....///" bypasses regexp's that remove "./" and "../"
https://www.cve.org/CVERecord?id=CVE-2005-0202

CVE-2004-1670
Mail server allows remote attackers to create arbitrary directories via a ".." or rename arbitrary files via a "....//" in user supplied parameters.
https://www.cve.org/CVERecord?id=CVE-2004-1670

File Processing

File or Directory

Relative Path Traversal

SFP16
Path Traversal

Allowed
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.
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.

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

Eric Dalci
Cigital
2008-07-01
updated References, Demonstrative_Example, Potential_Mitigations, Time_of_Introduction

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

CWE Content Team
MITRE
2008-10-14
updated Description

CWE Content Team
MITRE
2009-07-27
updated Potential_Mitigations

CWE Content Team
MITRE
2010-02-16
updated Demonstrative_Examples

CWE Content Team
MITRE
2010-06-21
updated Description, Potential_Mitigations

CWE Content Team
MITRE
2011-03-29
updated Potential_Mitigations

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences

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

CWE Content Team
MITRE
2014-07-30
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2017-01-19
updated Related_Attack_Patterns

CWE Content Team
MITRE
2017-11-08
updated Applicable_Platforms

CWE Content Team
MITRE
2019-06-20
updated Related_Attack_Patterns

CWE Content Team
MITRE
2020-02-24
updated Potential_Mitigations, Relationships

CWE Content Team
MITRE
2020-06-25
updated Observed_Examples, Potential_Mitigations

CWE Content Team
MITRE
2020-08-20
updated Relationships

CWE Content Team
MITRE
2020-12-10
updated Relationships

CWE Content Team
MITRE
2021-03-15
updated Demonstrative_Examples

CWE Content Team
MITRE
2021-10-28
updated Relationships

CWE Content Team
MITRE
2022-06-28
updated Observed_Examples

CWE Content Team
MITRE
2022-10-13
updated Alternate_Terms, Observed_Examples, References

CWE Content Team
MITRE
2023-01-31
updated Common_Consequences, Description

CWE Content Team
MITRE
2023-04-27
updated Detection_Factors, Relationships

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2023-10-26
updated Observed_Examples

CWE Content Team
MITRE
2024-07-16
4.15
2024-07-16
updated Observed_Examples, References

CWE Content Team
MITRE
2025-04-03
4.17
2025-04-03
updated Demonstrative_Examples

CWE Content Team
MITRE
2025-09-09
4.18
2025-09-09
updated Affected_Resources, Applicable_Platforms, Common_Consequences, Description, Diagram, Functional_Areas, Observed_Examples, Potential_Mitigations, References

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

Nick Johnston
2022-07-11
Identified weakness in Perl demonstrative example