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Fedora 45 Python 3.9 Fixes HTML Parser Denial-of

Linuxsecurity •LinuxSecurity Advisories • November 4, 2026

Two serious PHP flaws could let an attacker run code without logging in. See which setups and PHP versions are affected ×

Python 3.9 is an accessible, high-level, dynamically typed, interpreted

programming language, designed with an emphasis on code readability.

It includes an extensive standard library, and has a vast ecosystem of

third-party libraries.

The python3.9 package provides the "python3.9" executable: the reference

interpreter for the Python language, version 3.

The majority of its standard library is provided in the python3.9-libs package,

which should be installed automatically along with python3.9.

The remaining parts of the Python standard library are broken out into the

python3.9-tkinter and python3.9-test packages, which may need to be installed

Documentation for Python is provided in the python3.9-docs package.

Packages containing additional libraries for Python are generally named with

the "python3.9-" prefix.

Security fix for CVE-2026-11940 Security fix for CVE-2026-15308

* Wed Sep 23 2026 Miro Hrončok - 3.9.25-15 - Security fix for CVE-2026-11940 * Wed Sep 23 2026 Lukáš Zachar - 3.9.25-14 - Security fix for CVE-2026-15308 Resolves: rhbz#2498693

[ 1 ] Bug #2498693 - CVE-2026-15308 python3.9: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]

This update can be installed with the "dnf" update program. Use su -c 'dnf upgrade --advisory FEDORA-2026-7d4610faad' at the command line. For more information, refer to the dnf documentation available at

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Python 3.9 Security Flaws Addressed in Fedora Updates Fedora has released security updates for Python 3.9 addressing two vulnerabilities identified as CVE-2026-11940 and CVE-2026-15308. These vulnerabilities could allow attackers to execute code without authentication, impacting users of Fedora 43, 44, and 45. The flaws were published on June 23 and July 9, 2026, respectively, with a CVSS score of 7.8 and 8.7, indicating high severity. The updates were made available on September 23, 2026, and users are advised to upgrade their installations using the 'dnf' package manager. The vulnerabilities primarily affect systems running Fedora that utilize the Python 3.9 package. Security professionals should prioritize applying these updates to mitigate potential exploitation risks. 3 sources 58

Extracted Entities

Fedora 45 Python 3.9 Fixes HTML Parser Denial-of

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Extracted Entities

Attack Types (1)

CVEs (2)

CWE Weaknesses (1)

Platforms (1)