Debian dla-4532 : idle-python3.9 - security update

critical Nessus Plugin ID 307623

Synopsis

The remote Debian host is missing one or more security-related updates.

Description

The remote Debian 11 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4532 advisory.

- ------------------------------------------------------------------------- Debian LTS Advisory DLA-4532-1 [email protected] https://www.debian.org/lts/security/ Arnaud Rebillout April 15, 2026 https://wiki.debian.org/LTS
- -------------------------------------------------------------------------

Package : python3.9 Version : 3.9.2-1+deb11u6 CVE ID : CVE-2025-15366 CVE-2025-15367 CVE-2026-6100 Debian Bug :

It was found that the patches for CVE-2025-15366 and CVE-2025-15367 break backward compatibility, and upstream decided not to backport those patches to older Python releases. Therefore those 2 patches, applied in the previous version (python3.9 3.9.2-1+deb11u5), have been reverted.

Additionally, the following CVE have been fixed:

CVE-2026-6100

Use-after-free (UAF) was possible in the `lzma.LZMADecompressor` and `bz2.BZ2Decompressor` when a memory allocation fails with a `MemoryError` and the decompression instance is re-used. This scenario can be triggered if the process is under memory pressure.
The vulnerability is only present if the program re-uses decompressor instances across multiple decompression calls even after a `MemoryError` is raised during decompression. Using the helper functions to one-shot decompress data such as `lzma.decompress()` and `bz2.decompress()` are not affected as a new decompressor instance is used per call. If the decompressor instance is not re-used after an error condition, this usage is similarly not vulnerable.

For Debian 11 bullseye, these problems have been fixed in version 3.9.2-1+deb11u6.

We recommend that you upgrade your python3.9 packages.

For the detailed security status of python3.9 please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/python3.9

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Upgrade the idle-python3.9 packages.

Plugin Details

Severity: Critical

ID: 307623

File Name: debian_DLA-4532.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Debian Local Security Checks

Published: 4/20/2026

Updated: 4/20/2026

Supported Sensors: Continuous Assessment, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 8

Temporal Score: 5.9

Vector: CVSS2#AV:N/AC:L/Au:M/C:P/I:C/A:C

CVSS Score Source: CVE-2025-15367

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.2

Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

CVSS v4

Risk Factor: Critical

Base Score: 9.1

Threat Score: 6.9

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS Score Source: CVE-2026-6100

Vulnerability Information

CPE: p-cpe:/a:debian:debian_linux:idle-python3.9, p-cpe:/a:debian:debian_linux:libpython3.9-minimal, p-cpe:/a:debian:debian_linux:libpython3.9-dbg, cpe:/o:debian:debian_linux:11.0, p-cpe:/a:debian:debian_linux:python3.9, p-cpe:/a:debian:debian_linux:libpython3.9-dev, p-cpe:/a:debian:debian_linux:python3.9-minimal, p-cpe:/a:debian:debian_linux:python3.9-dbg, p-cpe:/a:debian:debian_linux:libpython3.9-testsuite, p-cpe:/a:debian:debian_linux:libpython3.9, p-cpe:/a:debian:debian_linux:python3.9-venv, p-cpe:/a:debian:debian_linux:python3.9-dev, p-cpe:/a:debian:debian_linux:libpython3.9-stdlib, p-cpe:/a:debian:debian_linux:python3.9-full, p-cpe:/a:debian:debian_linux:python3.9-examples, p-cpe:/a:debian:debian_linux:python3.9-doc

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Ease: No known exploits are available

Patch Publication Date: 4/15/2026

Vulnerability Publication Date: 1/20/2026

Reference Information

CVE: CVE-2025-15366, CVE-2025-15367, CVE-2026-6100

Detections

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