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Fencer Vulns
high 7.5

CVE-2026-42561 json

Python-Multipart: Denial of Service via unbounded multipart part headers

published 2026-05-06 6 mo ago modified 2026-10-26 14 d ago also EUVD-2026-30159 , GHSA-pp6c-gr5w-3c5g , PYSEC-2026-3039

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 54%
public exploits
0
none known

Summary

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.27, python-multipart has a denial of service vulnerability in multipart part header parsing. When parsing multipart/form-data, MultipartParser previously had no limit on the number of part headers or the size of an individual part header. An attacker could send a request with either many repeated headers without terminating the header block or a single very large header value, causing excessive CPU work before request rejection or completion. This vulnerability is fixed in 0.0.27.

Patch / fix

  • pypi python-multipart 0.0.27
  • Red Hat Red Hat Ansible Automation Platform 2.6 1783832856, 1783920640
  • Red Hat Red Hat Ansible Automation Platform 2.7 1783918403, 1783923914
  • Red Hat Red Hat Migration Toolkit for Applications 8.2 1784109883
  • Red Hat Red Hat OpenShift AI 3.3 1782887848
  • Red Hat Red Hat Satellite 6.17 1784834402
  • Red Hat Red Hat Satellite 6.19 1785806554, 1785929994
  • python-multipart Debian 14 0.0.32-1

debian advisories DEBIAN-CVE-2026-42561

  • python-python-multipart SLES for SAP applications 16.0, SLES 16.0 0.0.20-160000.4.1

suse advisories SUSE-SU-2026:21999-1

  • python-python-multipart openSUSE Tumbleweed 0.0.28-1.1

opensuse advisories openSUSE-SU-2026:10797-1

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-2026-42561 updated cvss 7.5

python-multipart: python-multipart: Denial of Service via excessive multipart part headers

  • Red Hat Exploit Intelligence exploit-intelligence-tech-preview/vulnerability-analysis-rhel9
    affected: no fix available
  • Red Hat AI Inference Server rhaiis/vllm-cpu-rhel9, rhaiis/vllm-tpu-rhel9, rhaiis/vllm-spyre-rhel9, rhaiis/vllm-neuron-rhel9 Red Hat Ansible Automation Platform 2 ansible-automation-platform-25/lightspeed-chatbot-rhel8
    affected: no fix planned “Will not fix”
  • 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/disk-image-cuda-rhel9, +2 more
    affected: no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-llama-stack-core-rhel9, rhoai/odh-caikit-tgis-serving-rhel9, rhoai/odh-trustyai-garak-lls-provider-dsp-rhel9 Red Hat Satellite 6 satellite/iop-host-inventory-rhel9
    affected: no fix available
  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/mcp-tools-rhel9 1783920640, ansible-automation-platform-26/lightspeed-chatbot-rhel9 1783832856
    fixed: vendor fix RHSA-2026:42132
  • Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/mcp-tools-rhel9 1783918403, ansible-automation-platform-27/lightspeed-chatbot-rhel9 1783923914
    fixed: vendor fix RHSA-2026:42142
  • Red Hat Migration Toolkit for Applications 8.2 mta/mta-solution-server-rhel9 1784109883
    fixed: vendor fix RHSA-2026:43038
  • Red Hat OpenShift AI 2.25 rhoai/odh-caikit-nlp-rhel9 1791448212
    fixed: vendor fix RHSA-2026:87410
show 6 more
  • Red Hat OpenShift AI 3.3 rhoai/odh-mlserver-rhel9 1782887848
    fixed: vendor fix RHSA-2026:37275
  • Red Hat Satellite 6.17 satellite/iop-advisor-engine-rhel9 1784834402
    fixed: vendor fix RHSA-2026:44696
  • Red Hat Satellite 6.18 satellite/iop-vulnerability-engine-rhel9 1784554123
    fixed: vendor fix RHSA-2026:51357
  • Red Hat Satellite 6.19 satellite/iop-vmaas-rhel9 1785929994, satellite/iop-vulnerability-engine-rhel9 1785806554
    fixed: vendor fix RHSA-2026:51194
  • Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-ocp-rag-rhel9, openshift-lightspeed/lightspeed-service-api-rhel9
    not affected: vulnerable code not in execute path
  • Red Hat AI Inference Server rhaiis/vllm-cuda-rhel9, rhaiis/vllm-rocm-rhel9 Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/hub-rhel9 1783979593, ansible-automation-platform-26/gateway-rhel9 1783969842, ansible-automation-platform-26/hub-web-rhel9 1783982443, ansible-automation-platform-26/receptor-rhel9 1783962464, ansible-automation-platform-26/controller-rhel9 1783973764, ansible-automation-platform-26/de-minimal-rhel9 1783921549, +23 more Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/hub-rhel9 1783919521, ansible-automation-platform-27/gateway-rhel9 1783919486, ansible-automation-platform-27/hub-web-rhel9 1783921568, ansible-automation-platform-27/receptor-rhel9 1783917963, ansible-automation-platform-27/controller-rhel9 1783921344, ansible-automation-platform-27/de-minimal-rhel9 1783918892, +24 more Red Hat Migration Toolkit for Applications 8.2 mta/mta-ui-rhel9 1783962515, mta/mta-cli-rhel9 1784211378, mta/mta-hub-rhel9 1784059743, mta/mta-rhel9-operator 1784219586, mta/mta-operator-bundle 1784220119, mta/mta-analyzer-addon-rhel9 1784163267, +7 more Red Hat OpenShift AI (RHOAI) rhoai/odh-vllm-cuda-rhel9, rhoai/odh-vllm-rocm-rhel9, rhoai/odh-vllm-gaudi-rhel9, rhoai/odh-kserve-agent-rhel9, rhoai/odh-kserve-router-rhel9, rhoai/odh-feature-server-rhel9, +2 more Red Hat OpenShift AI 2.25 rhoai/odh-rhel9-operator 1792570619, rhoai/odh-vllm-cpu-rhel9 1792018436, rhoai/odh-dashboard-rhel9 1791853525, rhoai/odh-modelmesh-rhel9 1790881700, rhoai/odh-operator-bundle 1792571069, rhoai/odh-vllm-cuda-rhel9 1791358976, +65 more
    +2 more products
    Red Hat OpenShift AI 3.3 rhoai/odh-cli-rhel9 1782471642, rhoai/rhai-cli-rhel9 1782471642, rhoai/odh-mlflow-rhel9 1782917849, rhoai/odh-trainer-rhel9 1782471656, rhoai/odh-maas-api-rhel9 1782996644, rhoai/odh-rhel9-operator 1783085334, +76 more Red Hat Satellite 6 satellite/foreman-mcp-server-rhel9
    not affected: vulnerable code 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
yes
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.74% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi python-multipart
<0.0.27
0.0.27

Affected products

  • Kludex python-multipart
  • Red Hat Red Hat Ansible Automation Platform 2.6
  • Red Hat Red Hat Ansible Automation Platform 2.7
  • Red Hat Red Hat Migration Toolkit for Applications 8.2
  • Red Hat Red Hat OpenShift AI 3.3
  • Red Hat Red Hat Satellite 6.17
  • Red Hat Red Hat Satellite 6.19
  • Red Hat Exploit Intelligence
  • Red Hat OpenShift Lightspeed
  • Red Hat Red Hat AI Inference Server
  • Red Hat Red Hat Ansible Automation Platform 2
  • Red Hat Red Hat Enterprise Linux AI (RHEL AI) 3
  • Red Hat Red Hat OpenShift AI (RHOAI)
  • Red Hat Red Hat Satellite 6

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling
  • CWE-606 Unchecked Input for Loop Condition

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.