miurahr py7zr up to 1.1.2 link following

Summaryinfo

A vulnerability was found in miurahr py7zr up to 1.1.2. It has been rated as critical. This vulnerability affects unknown code. The manipulation leads to link following. This vulnerability is documented as CVE-2026-23879. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in miurahr py7zr up to 1.1.2 and classified as critical. This issue affects an unknown function. The manipulation with an unknown input leads to a link following vulnerability. Using CWE to declare the problem leads to CWE-59. The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Versions 1.1.2 and below contain an an arbitrary file write vulnerability, which allows symbolic links to be recreated outside the destination directory via crafted malicious symbolic link chains. When using extractall to extract an archive, the library restores these symbolic links, linking them to arbitrary directories on the host file system. During extraction, the program only checks the link arcname within the destination directory, but ignores the combined symlink path resolution. Attackers can exploit this vulnerability by constructing malicious archives, thereby bypassing the directory boundary restrictions implemented by the extractor. Subsequent extraction of regular files through these symbolic links can result in arbitrary file writes. This vulnerability may lead to remote code execution, privilege escalation, data corruption, or denial of service. This issue has been fixed in version 1.1.3.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-23879 since 01/16/2026. The exploitation is known to be easy. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available.

Upgrading to version 1.1.3 eliminates this vulnerability. The upgrade is hosted for download at github.com.

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Productinfo

Vendor

• miurahr

Name

• py7zr

Version

• 1.1.0
• 1.1.1
• 1.1.2

Website

• Product: https://github.com/miurahr/py7zr/

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