Caleb Brown

An open redirect occurs when the software normalizes the HTTP Location header to include the request hostname. The process involves parsing the redirect URL using Python's `urllib.parse` and joining it to the base URL. Because `urlsplit` (called internally by `urljoin`) treats a `//` at the start of a string as a URI without a scheme, it interprets the subsequent part as the hostname, replacing the original request hostname. Although a previous attempt was made to mitigate this by replacing `//` with `/%2f`, Python 3.10 and later versions of `urlsplit` internally strip ASCII tab, carriage return, and newline characters. Consequently, a string such as `/t/attacker.com` is converted to `//attacker.com`, bypassing the previous fix and allowing redirection to an external domain.

The 'zipfile' module does not validate the ZIP64 End of Central Directory (EOCD) Locator record offset value, leading to potential discrepancies in how ZIP archives are handled compared to other ZIP implementations. Specifically, the module incorrectly assumes the ZIP64 EOCD record's location, potentially allowing crafted ZIP archives to be processed in an unexpected manner.

An issue in the `tarfile` module allows the extraction filter to be ignored when extracting untrusted tar archives. This can enable an attacker to create symbolic links that point outside the destination directory, modify file metadata, and potentially modify files in arbitrary filesystem locations, leading to data loss or unauthorized access to protected information. The issue occurs when using the `TarFile.extractall()` or `TarFile.extract()` functions with the `filter` parameter set to `data` or `tar`. For Python versions 3.14 and later, the default value of the `filter` parameter is `data`, making usage relying on this default behavior also susceptible.

The issue allows the extraction filter to be ignored, enabling symlink targets to point outside the destination directory and the modification of some file metadata. This affects users who utilize the tarfile module to extract untrusted tar archives using TarFile.extractall() or TarFile.extract() with the filter parameter set to "data" or "tar". For Python 3.14 and later, the default filter value changed to "data", which also affects usage relying on this new default behavior. The installation of source distributions, which are tar archives, is not significantly affected as they already allow arbitrary code execution during the build process.

An issue in the `tarfile` module allows arbitrary filesystem writes outside the extraction directory when extracting untrusted tar archives. This occurs when using the `TarFile.extractall()` or `TarFile.extract()` functions with the `filter` parameter set to `data` or `tar`. For Python 3.14 and later, the default value of `filter` changed to `data`, making usage relying on this default behavior also susceptible. An attacker could exploit this to modify files in arbitrary locations, cause data loss, or potentially achieve privilege escalation or container escape if the scripts are executed with root privileges.