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Fencer Vulns
medium 6.3

CVE-2026-3276 json

Potential DoS via quadratic complexity in unicodedata.normalize()

published 2026-06-03 5 mo ago modified 2026-08-19 2 mo ago also BIT-libpython-2026-3276 , BIT-python-2026-3276 , BIT-python-min-2026-3276 , EUVD-2026-34103

cvss
6.3
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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.

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, 3.15.0b2
  • 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-2026-3276

  • 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-2026-3276

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

  • 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
  • grafana Multi Linux Manager Tools SLE-15 12.4.10-150002.4.27.1
  • mgr-push Multi Linux Manager Tools SLE-15 5.2.5-150002.3.12.1
  • spacecmd Multi Linux Manager Tools SLE-15 5.2.10-150002.3.15.1
  • uyuni-tools Multi Linux Manager Tools SLE-Micro-5, Multi Linux Manager Tools SLE-15 5.2.17-150002.3.20.1
  • venv-salt-minion Multi Linux Manager Tools SLE-Micro-5, Multi Linux Manager Tools SLE-15 3006.0-150002.5.22.1
  • spacewalk-client-tools Multi Linux Manager Tools SLE-15 5.2.7-150002.3.12.1

suse advisories SUSE-SU-2026:4754-1SUSE-SU-2026:4744-1SUSE-SU-2026:4743-1SUSE-SU-2026:4585-1SUSE-SU-2026:4584-1SUSE-SU-2026:4583-1

  • python313 openSUSE Tumbleweed 3.13.14-2.1
  • python310 openSUSE Tumbleweed 3.10.20-8.1
  • python311 openSUSE Tumbleweed 3.11.15-8.1
  • python312 openSUSE Tumbleweed 3.12.13-8.1
  • python314 openSUSE Tumbleweed 3.14.6-1.1
  • python315 openSUSE Tumbleweed 3.15.0~b2-1.1

opensuse advisories openSUSE-SU-2026:11534-1openSUSE-SU-2026:11426-1openSUSE-SU-2026:11427-1openSUSE-SU-2026:11428-1openSUSE-SU-2026:11181-1openSUSE-SU-2026:11101-1

  • python3 Alpine 3.24 3.14.7-r0

alpine advisories ALPINE-CVE-2026-3276

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-89466

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-2026-3276 updated cvss 5.3

python: Python unicodedata: Denial of Service due to excessive CPU consumption

  • Red Hat Exploit Intelligence exploit-intelligence-tech-preview/vulnerability-analysis-rhel9 Red Hat AI Inference Server rhaii/vllm-cpu-rhel9, rhaii/vllm-tpu-rhel9, rhaii/vllm-cuda-rhel9, rhaii/vllm-rocm-rhel9, rhaiis/vllm-cpu-rhel9, rhaiis/vllm-tpu-rhel9, +9 more Red Hat Enterprise Linux 6 python, tkinter, python-libs, python-test, python-tools Red Hat Enterprise Linux 7 python, python3, tkinter, python-libs, python-test, python-tools, +4 more Red Hat Enterprise Linux 8 scipy, python3, python36, python3.12, python-nose, python-wheel, +31 more Red Hat Enterprise Linux 9 python3, python3.9, python3.12, python3.14, python3-idle, python3-libs, +16 more
    +3 more products
    Red Hat Enterprise Linux 10 python3.12, python3.14 Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/bootc-aws-cuda-rhel9, rhelai3/bootc-gcp-cuda-rhel9, rhelai3/bootc-azure-cuda-rhel9, +1 more Red Hat OpenShift AI (RHOAI) rhoai/rhai-cli-rhel9, rhoai/odh-automl-rhel9, rhoai/odh-mlflow-rhel9, rhoai/odh-autorag-rhel9, rhoai/odh-mlserver-rhel9, rhai/base-image-cpu-rhel9, +60 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
5 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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-407 Inefficient Algorithmic Complexity

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.