CVE-2026-115791Python Software Foundation CPython inclusion of untrusted functionality
CVE-2026-115791 is a inclusion of untrusted functionality in Python Software Foundation CPython, rated medium (5.3 on CVSS 4.0).
Why this priority: Medium severity, with no exploitation signal.
Published · Updated · NVD status: Awaiting Analysis
What it is
The product loads code from a source outside its control.
How it is reached
An attacker can exploit it by someone who can already run code or sign in on the machine, with an ordinary user account, but someone has to act first, such as opening a file or following a link. Success also depends on conditions the attacker does not fully control.
What an attacker gains
A successful attack can read the data it protects and change data or behaviour. In practice, this kind of flaw lets an attacker run their code inside your build or your running service.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Upgrade Python Software Foundation CPython to 3.16.0 or later.
- Limit who can run code or sign in on the hosts that run it.
- Warn the people who use it, and filter files and links on the way in.
Description from NVD
When tarfile or zipfile command line interface (CLI) is used to
decompress an archive, a Python script shadowing the stdlib can be
created. Then if an error occurs during decompressing the next file,
the newly created Python script is executed. This is especially true
if the created Python is called traceback.py. The problem is that
Python adds the current directory to sys.path when python -m MODULE is
run, and the archive is also decompressed in the current directory.
The fix removes sys.path[0] in gzip, tarfile and zipfile command line
interface to prevent shadowing standard library modules from extracted
files.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Build pipelines, dependencies and plugins. The flaw sits between third-party code and your build or runtime.
- Update channels. The flaw sits between third-party code and your build or runtime.
Trust boundaries in play
- Host boundary. The attacker needs a foothold on the machine first; the flaw turns a small foothold into a bigger one.
- People who open files and links. Mail, chat and browsers are the delivery path.
- Between third-party code and your build or runtime. An attacker who crosses it can run their code inside your build or your running service.
Questions to answer about your own systems
- Where does Python Software Foundation CPython run in your systems, and at which version?
- Which of those hosts also run code or users you do not fully trust?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.