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Fencer Vulns
high 8.2

CVE-2026-9669 json

bz2.BZ2Decompressor reuse after error can cause a stack buffer overflow

published 2026-06-08 5 mo ago modified 2026-08-19 2 mo ago also BIT-libpython-2026-9669 , BIT-python-2026-9669 , BIT-python-min-2026-9669 , EUVD-2026-35202

cvss
8.2
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

bz2.BZ2Decompressor objects could be reused after a decompression error. If an application caught the resulting OSError and retried with the same decompressor, crafted input could cause the decompressor to resume from an invalid internal state and perform out-of-bounds writes to a stack buffer. This could crash the process when processing untrusted data.

Patch / fix

  • bitnami libpython 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6
  • bitnami python 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6
  • bitnami python-min 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6
  • Python Software Foundation CPython 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6, 3.15.0b3
  • python3.11 Debian 12 3.11.2-6+deb12u9
  • python3.13 Debian 13 3.13.5-2+deb13u3
  • python3.14 Debian 14 3.14.6-1

debian advisories DEBIAN-CVE-2026-9669

  • python3.10 Ubuntu 22.04 LTS 3.10.12-1~22.04.16
  • python3.12 Ubuntu 24.04 LTS 3.12.3-1ubuntu0.15
  • python3.14 Ubuntu 26.04 LTS 3.14.4-1ubuntu0.1

ubuntu advisories UBUNTU-CVE-2026-9669

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python3.13 hummingbird 1 3.13.15-1.3.hum1
  • python3.13-idle hummingbird 1 3.13.15-1.3.hum1
  • python3.13-libs hummingbird 1 3.13.15-1.3.hum1
  • python3.13-test hummingbird 1 3.13.15-1.3.hum1
  • python3.13-tkinter hummingbird 1 3.13.15-1.3.hum1
  • python3.13-freethreading hummingbird 1 3.13.15-1.3.hum1
  • python3.12 hummingbird 1 3.12.14-1.3.hum1
  • python3.12-idle hummingbird 1 3.12.14-1.3.hum1

red hat advisories RHSA-2026:68309RHSA-2026:68154RHSA-2026:68135RHSA-2026:68132RHSA-2026:67572

  • python311 SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Python 3 15 SP7 3.11.17-150600.3.74.1
  • python311-core SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Python 3 15 SP7 +1 more 3.11.17-150600.3.74.1
  • python3 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 3.6.15-150300.10.129.1
  • python3-core SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +12 more 3.6.15-150300.10.129.1
  • python SLE Module for Package Hub 15 SP7 2.7.18-150000.133.1
  • python-base SLE Module for Package Hub 15 SP7 2.7.18-150000.133.1
  • python313 SLE Module for Python 3 15 SP7 3.13.15-150700.4.56.1
  • python313-core SLE Module for Python 3 15 SP7 3.13.15-150700.4.56.1

suse advisories SUSE-SU-2026:4946-1SUSE-SU-2026:4754-1SUSE-SU-2026:4744-1SUSE-SU-2026:4743-1SUSE-SU-2026:4633-1SUSE-SU-2026:4534-1

  • python313 openSUSE Tumbleweed 3.13.15-1.1
  • python311 openSUSE Tumbleweed 3.11.16-1.1
  • python312 openSUSE Tumbleweed 3.12.14-1.1
  • python310 openSUSE Tumbleweed 3.10.21-1.1
  • python315 openSUSE Tumbleweed 3.15.0~rc2-1.1
  • python314 openSUSE Tumbleweed 3.14.6-1.1

opensuse advisories openSUSE-SU-2026:11817-1openSUSE-SU-2026:11756-1openSUSE-SU-2026:11757-1openSUSE-SU-2026:11747-1openSUSE-SU-2026:11748-1openSUSE-SU-2026:11181-1

  • python3 Alpine 3.24 3.14.7-r0

alpine advisories ALPINE-CVE-2026-9669

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python3 Azure Linux 3.0 3.12.9-14

azure linux advisories AZL-90159

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-9669 updated cvss 5.9

python: Python: Denial of Service via out-of-bounds write in BZ2 decompression

  • Red Hat Enterprise Linux 8 scipy, python36, python-nose, python-wheel, python3-bson, python3-nose, +19 more
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images python3 3.14.7-1.2.hum1, python3.14 3.14.7-1.2.hum1, python3.10 3.10.21-1.3.hum1, python3.11 3.11.16-1.4.hum1, python3.12 3.12.14-1.3.hum1, python3.13 3.13.15-1.3.hum1, +27 more
    fixed: vendor fix RHSA-2026:67572
  • Red Hat Hardened Images hi/python
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 8.2 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 4.0 8.2 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
bitnami libpython
<3.10.21
>=3.11.0, <3.11.16
>=3.12.0, <3.12.14
>=3.13.0, <3.13.14
>=3.14.0, <3.14.6
3.10.21
3.11.16
3.12.14
3.13.14
3.14.6
bitnami python
<3.10.21
>=3.11.0, <3.11.16
>=3.12.0, <3.12.14
>=3.13.0, <3.13.14
>=3.14.0, <3.14.6
3.10.21
3.11.16
3.12.14
3.13.14
3.14.6
bitnami python-min
<3.10.21
>=3.11.0, <3.11.16
>=3.12.0, <3.12.14
>=3.13.0, <3.13.14
>=3.14.0, <3.14.6
3.10.21
3.11.16
3.12.14
3.13.14
3.14.6

Affected products

  • Python Software Foundation CPython

Classification

Weakness
  • CWE-121 Stack-based Buffer Overflow

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.