{"id":86439,"date":"2026-02-11T13:13:31","date_gmt":"2026-02-11T13:13:31","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T00:00:00","slug":"cve-2025-4138-python-tarfile-module-vulnerability-allowing-metadata-modification-and-symlink-targets-modification","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-4138-python-tarfile-module-vulnerability-allowing-metadata-modification-and-symlink-targets-modification\/","title":{"rendered":"CVE-2025-4138: Python Tarfile Module Vulnerability Allowing Metadata Modification and Symlink Targets Modification<\/strong>"},"content":{"rendered":"

Overview<\/strong><\/p>\n

This report covers the CVE-2025-4138 vulnerability, a significant flaw in the Python tarfile module. This vulnerability allows the extraction filter to be bypassed, enabling symlink targets to point outside the destination directory and the modification of some file metadata. This affects developers and organizations that employ the tarfile module to extract untrusted tar archives using specific parameters. The vulnerability is of particular concern due to its potential for system compromise or data leakage.<\/p>\n

Vulnerability Summary<\/strong><\/p>\n

CVE ID: CVE-2025-4138
\nSeverity: High (7.5 CVSS score)
\nAttack Vector: Network
\nPrivileges Required: Low
\nUser Interaction: None
\nImpact: Potential system compromise and data leakage<\/p>\n

Affected Products<\/strong><\/p>\n

Product | Affected Versions<\/p>\n

Python Tarfile Module | Python 3.14 or later<\/p>\n

How the Exploit Works<\/strong><\/p>\n

The exploit operates by bypassing the extraction filter in the Python tarfile module, allowing symlink targets to point outside the destination directory. This allows an attacker to modify file metadata and potentially extract data or compromise the system. The exploit specifically targets the use of TarFile.extractall() or TarFile.extract() with the filter= parameter with a value of “data” or “tar”.<\/p>\n

Conceptual Example Code<\/strong><\/p>\n

Here is a conceptual example of how the vulnerability might be exploited:<\/p>\n

import tarfile\ndef malicious_extract(tar_path, extract_path):\nwith tarfile.open(tar_path) as tar:\nfor member in tar.getmembers():\nif '..' in member.name:\ncontinue\ntar.extract(member, path=extract_path, set_attrs=False)\nmalicious_extract('untrusted_archive.tar', '\/safe\/directory\/')<\/code><\/pre>\n
In this example, the `malicious_extract` function opens a tar file and iterates over its members. If a member’s name contains ‘..’, symbolizing a path above the current directory level, it is ignored, and the extraction continues, potentially allowing harmful code execution or data extraction.<\/p>\n","protected":false},"excerpt":{"rendered":"
Overview This report covers the CVE-2025-4138 vulnerability, a significant flaw in the Python tarfile module. This vulnerability allows the extraction filter to be bypassed, enabling symlink targets to point outside the destination directory and the modification of some file metadata. This affects developers and organizations that employ the tarfile module to extract untrusted tar archives […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[],"tags":[],"vendor":[],"product":[],"attack_vector":[],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-86439","post","type-post","status-publish","format-standard","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t