cve.bz

CAPEC-139

Relative Path Traversal

High severityHigh likelihoodDetailed pattern

An attacker exploits a weakness in input validation on the target by supplying a specially constructed path utilizing dot and slash characters for the purpose of obtaining access to arbitrary files or resources. An attacker modifies a known path on the target in order to reach material that is not available through intended channels. These attacks normally involve adding additional path separators (/ or \) and/or dots (.), or encodings thereof, in various combinations in order to reach parent directories or entirely separate trees of the target's directory structure.

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Show the promptExplain the attack pattern CAPEC-139: Relative Path Traversal: how it unfolds, what it needs and how to prevent and detect it in my systems. Use https://capec.mitre.org/data/definitions/139.html and https://cve.bz/cve/capec/139?via=ask-ai-copy, which lists recent CVEs with the weaknesses it exploits. Cite the sources.

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How the attack unfolds

  1. Explore

    The attacker looks for a way in.

    1. [Fingerprinting of the operating system] In order to perform a valid path traversal, the adversary needs to know what the underlying OS is so that the proper file seperator is used.

      3 techniques
      • Port mapping. Identify ports that the system is listening on, and attempt to identify inputs and protocol types on those ports.
      • TCP/IP Fingerprinting. The adversary uses various software to make connections or partial connections and observe idiosyncratic responses from the operating system. Using those responses, they attempt to guess the actual operating system.
      • Induce errors to find informative error messages

    2. [Survey application] Using manual or automated means, an adversary will survey the target application looking for all areas where user input is taken to specify a file name or path.

      3 techniques
      • Use a spidering tool to follow and record all links on a web page. Make special note of any links that include parameters in the URL.
      • Use a proxy tool to record all links visited during a manual traversal of a web application. Make special note of any links that include parameters in the URL. Manual traversal of this type is frequently necessary to identify forms that are GET method forms rather than POST forms.
      • Use a browser to manually explore a website and analyze how it is constructed. Many browser plug-ins are available to facilitate the analysis or automate the URL discovery.

  2. Experiment

    They probe what they found.

    1. [Attempt variations on input parameters] Using manual or automated means, an adversary attempts varying relative file path combinations on all found user input locations and observes the responses.

      3 techniques
      • Provide "../" or "..\" at the beginning of any filename to traverse to the parent directory
      • Use a list of probe strings as path traversal payload. Different strings may be used for different platforms. Strings contain relative path sequences such as "../".
      • Use a proxy tool to record results of manual input of relative path traversal probes in known URLs.

  3. Exploit

    They carry out the attack.

    1. [Access, modify, or execute arbitrary files.] An adversary injects path traversal syntax into identified vulnerable inputs to cause inappropriate reading, writing or execution of files. An adversary could be able to read directories or files which they are normally not allowed to read. The adversary could also access data outside the web document root, or include scripts, source code and other kinds of files from external websites. Once the adversary accesses arbitrary files, they could also modify files. In particular situations, the adversary could also execute arbitrary code or system commands.

      2 techniques
      • Manipulate file and its path by injecting relative path sequences (e.g. "../").
      • Download files, modify files, or try to execute shell commands (with binary files).

Prerequisites

  • The target application must accept a string as user input, fail to sanitize combinations of characters in the input that have a special meaning in the context of path navigation, and insert the user-supplied string into path navigation commands.

Skills required

  • Low skill

    To inject the malicious payload in a web page

  • High skill

    To bypass non trivial filters in the application

Consequences

What a successful attack can lead to
ImpactAffectsNote
Modify DataIntegrity
Read DataConfidentiality
Execute Unauthorized CommandsConfidentiality, Integrity, AvailabilityRun Arbitrary Code
Bypass Protection MechanismAccess Control
Unreliable ExecutionAvailability

Mitigations

  • Design: Input validation. Assume that user inputs are malicious. Utilize strict type, character, and encoding enforcement

  • Implementation: Perform input validation for all remote content, including remote and user-generated content.

  • Implementation: Validate user input by only accepting known good. Ensure all content that is delivered to client is sanitized against an acceptable content specification -- using an allowlist approach.

  • Implementation: Prefer working without user input when using file system calls

  • Implementation: Use indirect references rather than actual file names.

  • Implementation: Use possible permissions on file access when developing and deploying web applications.

Weaknesses it exploits

  • CWE-23 Relative Path Traversal

Recent CVEs with these weaknesses

  1. 5.9CVE-2026-124034

    Relative path traversal in the local hybrid job input data download in Amazon Braket SDK before 1.127.7 might allow a remote authenticated user with S3 write access to a hybrid job's input data location to overwrite arbitrary files with th…

  2. 5.9CVE-2026-124033

    The export-cluster-logs and export-image-logs commands in the AWS ParallelCluster CLI before version 3.16.0 contain a relative path traversal issue. An authenticated remote user with write access to the log export Amazon S3 bucket could us…

  3. 8.5CVE-2026-104620

    A path traversal attack in simulation of actions in the Zypp backend of PackageKit before 1.4.1 could be used by local attackers to gain root privileges.

  4. 5.0CVE-2026-123973

    SharePoint Products CopyMove before 2026-11-06 allows traversal. An authenticated SharePoint user with the necessary permissions to use the ZIP import functionality may exploit a path traversal vulnerability in CopyMove for SharePoint 2019…

  5. 4.4CVE-2026-62855

    FreeScout is a self-hosted help desk and shared mailbox. Prior to 1.8.225, the administrator-only App Logs viewer accepts Laravel-encrypted folder and file parameters whose constructed path is checked only as a raw string. An administrator…

  6. 3.3CVE-2026-123845

    In JetBrains IntelliJ IDEA before 2026.3 path traversal was possible via JSON Schema references in untrusted projects

  7. 7.5CVE-2026-123305

    In JetBrains IntelliJ IDEA before 2026.3 path traversal was possible via unpacking Dev Container archives from a remote host

  8. 6.9CVE-2026-63499

    zt-zip is a Java library that provides convenience methods for ZIP archive manipulation. Prior to 1.18.1, ZipUtil.unpack(...) can apply stored ZIP-entry permissions to the extraction output directory when an entry name such as / or ./ reso…

The newest records naming one of them. Each weakness's page lists them all.

Part of

Examples

The attacker uses relative path traversal to access files in the application. This is an example of accessing…

The attacker uses relative path traversal to access files in the application. This is an example of accessing user's password file.

http://www.example.com/getProfile.jsp?filename=../../../../etc/passwd

However, the target application employs regular expressions to make sure no relative path sequences are being passed through the application to the web page. The application would replace all matches from this regex with the empty string.

Then an attacker creates special payloads to bypass this filter:

http://www.example.com/getProfile.jsp?filename=%2e%2e/%2e%2e/%2e%2e/%2e%2e /etc/passwd

When the application gets this input string, it will be the desired vector by the attacker.

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