OESA-2026-3069

Python combines remarkable power with very clear syntax. It has modules, classes, exceptions, very high level dynamic data types, and dynamic typing. There are interfaces to many system calls and libraries, as well as to various windowing systems. New built-in modules are easily written in C or C++ (or other languages, depending on the chosen implementation). Python is also usable as an extension language for applications written in other languages that need easy-to-use scripting or automation interfaces.

Security Fix(es):

When using the "configparser" module to write configuration files containing multi-line text values with carriage return characters (\r) the resulting file could be injected with unexpected keys and values if the attacker controls the written value.(CVE-2026-0864)

tarfile.extractall() with the 'data' or 'tar' filter could be bypassed by a crafted archive where a hardlink references a symlink stored at a deeper name than the hardlink itself.  The extraction fallback validated the symlink at it's archived location but recreated it at the hardlink's shallower path, letting a relative target the filter judged contained escape the destination directory.  This allowed a malicious tar archive to create a symlink pointing outside the destination, enabling out-of-destination file reads or writes. This was an incomplete fix of CVE-2025-4330.(CVE-2026-11940)

When using the "tarfile" module with a file opened in "streaming mode" (mode="r|") the tarfile module did not properly handle EOF, making archive parsing take exponentially longer.(CVE-2026-11972)

unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long runs of combining characters with alternating Canonical Combining Class values. This affects all normalization forms.(CVE-2026-3276)

The ftpcp() function in Lib/ftplib.py was not updated when CVE-2021-4189 was fixed. While makepasv() was patched to replace server-supplied PASV host addresses with the actual peer address (getpeername()[0]), ftpcp() still calls parse227() directly and passes the raw attacker-controllable IP address and port to target.sendport(). This patch is related to CVE-2021-4189.(CVE-2026-8328)