Python-Multipart: Denial of Service via unbounded multipart part headers
Priority MEDIUM 40CWE-770Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 8 fixed, 6 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-770.
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0074 54th percentileScored 2026-11-07
Fix Partial python-multipart (Kludex): 0.0.27python-multipart (PyPI): 0.0.27Red Hat: 9 advisoriesRed Hat: 8 fixed, 6 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Kludex | python-multipart | before 0.0.27 | 0.0.27 | Patch available | CNA |
| — | python-multipart (PyPI) | before 0.0.27 | 0.0.27 | Patch available | GHSA-pp6c-gr5w-3c5g |
- python-multipart VendorKludex Affected before 0.0.27 Fixed in 0.0.27 Patch available CNA
- python-multipart (PyPI) Vendor— Affected before 0.0.27 Fixed in 0.0.27 Patch available GHSA-pp6c-gr5w-3c5g
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:fastapiexpert:python-multipart:*:*:*:*:*:*:*:* | — | — | Fastapiexpert |
- cpe:2.3:a:fastapiexpert:python-multipart:*:*:*:*:*:*:*:* Versions — — ·Fastapiexpert
Remediation
- Fix · CNA python-multipart (Kludex) Fixed in 0.0.27
- Fix · GHSA-pp6c-gr5w-3c5g python-multipart (PyPI) Fixed in 0.0.27 Advisory →
Red Hat 9 advisories
- RHSA-2026:87410 Released 2026-10-21 · Red Hat rating CriticalRHOAI 2.25.12 - Red Hat OpenShift AI
- Red Hat OpenShift AI 2.25 registry.redhat.io/rhoai/odh-built-in-detector-rhel9, registry.redhat.io/rhoai/odh-caikit-nlp-rhel9, registry.redhat.io/rhoai/odh-codeflare-operator-rhel9 +47
- RHSA-2026:51357 Released 2026-08-06 · Red Hat rating Importantsatellite/iop-vulnerability-engine-rhel9 container image available as a Technology Preview
- Red Hat Satellite 6.18 registry.redhat.io/satellite/iop-vulnerability-engine-rhel9
- RHSA-2026:51219 Released 2026-08-06 · Red Hat rating Importantsatellite/iop-vulnerability-engine-rhel9 container image available as a Technology Preview
- Red Hat Satellite 6.19 registry.redhat.io/satellite/iop-vulnerability-engine-rhel9
Show 6 more Red Hat advisories
- RHSA-2026:51194 Released 2026-08-06 · Red Hat rating ImportantTechnical preview of the satellite/iop-vmaas-rhel9 container image
- Red Hat Satellite 6.19 registry.redhat.io/satellite/iop-vmaas-rhel9
- RHSA-2026:44696 Released 2026-07-23 · Red Hat rating Importantsatellite/iop-advisor-engine-rhel9 container image available as a Technology Preview
- Red Hat Satellite 6.17 registry.redhat.io/satellite/iop-advisor-engine-rhel9
- RHSA-2026:43038 Released 2026-07-21 · Red Hat rating CriticalMigration Toolkit for Applications
- Red Hat Migration Toolkit for Applications 8.2 registry.redhat.io/mta/mta-cli-rhel9, registry.redhat.io/mta/mta-solution-server-rhel9
- RHSA-2026:42142 Released 2026-07-20 · Red Hat rating ImportantRed Hat Ansible Automation Platform 2.7 Container Release Update
- Red Hat Ansible Automation Platform 2.7 registry.redhat.io/ansible-automation-platform-27/gateway-rhel9, registry.redhat.io/ansible-automation-platform-27/hub-rhel9, registry.redhat.io/ansible-automation-platform-27/lightspeed-chatbot-rhel9 +3
- RHSA-2026:42132 Released 2026-07-20 · Red Hat rating ImportantRed Hat Ansible Automation Platform 2.6 Container Release Update
- Red Hat Ansible Automation Platform 2.6 registry.redhat.io/ansible-automation-platform-26/controller-rhel9, registry.redhat.io/ansible-automation-platform-26/de-minimal-rhel9, registry.redhat.io/ansible-automation-platform-26/de-supported-rhel9 +7
- RHSA-2026:37275 Released 2026-07-09 · Red Hat rating CriticalRHOAI 3.3.5 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.3 registry.redhat.io/rhoai/odh-dashboard-rhel9, registry.redhat.io/rhoai/odh-data-science-pipelines-operator-controller-rhel9, registry.redhat.io/rhoai/odh-feast-operator-rhel9 +45
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Exploit Intelligence | Affected | No fix yet |
| Red Hat AI Inference Server | Affected | No fix planned: Will not fix |
| Red Hat Ansible Automation Platform 2 | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet |
| Red Hat Satellite 6 | Affected | No fix yet |
| Red Hat Ansible Automation Platform 2.6 | Fixed | RHSA-2026:42132 |
| Red Hat Ansible Automation Platform 2.7 | Fixed | RHSA-2026:42142 |
| Red Hat Migration Toolkit for Applications 8.2 | Fixed | RHSA-2026:43038 |
| Red Hat OpenShift AI 2.25 | Fixed | RHSA-2026:87410 |
| Red Hat OpenShift AI 3.3 | Fixed | RHSA-2026:37275 |
| Red Hat Satellite 6.17 | Fixed | RHSA-2026:44696 |
| Red Hat Satellite 6.18 | Fixed | RHSA-2026:51357 |
| Red Hat Satellite 6.19 | Fixed | RHSA-2026:51194, RHSA-2026:51219 |
Not affected: 9 products
- OpenShift Lightspeed
- Red Hat AI Inference Server
- Red Hat Ansible Automation Platform 2.6
- Red Hat Ansible Automation Platform 2.7
- Red Hat Migration Toolkit for Applications 8.2
- Red Hat OpenShift AI (RHOAI)
- Red Hat OpenShift AI 2.25
- Red Hat OpenShift AI 3.3
- Red Hat Satellite 6
Timeline
- 2026-10-02 Threatist record created from CVE-2026-42561
- 2026-10-03 Alias added: GHSA-pp6c-gr5w-3c5g
- 2026-10-22 Fix available: RHSA-2026:87410 · Red Hat
- 2026-10-23 Fix available: Red Hat OpenShift AI 2.25 · Red Hat
References
More Kludex vulnerabilities
- TI-2025-38917 Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse CVSS 3.1HIGH 7.5
- TI-2024-36140 python-multipart has a Denial of service (DoS) via deformation `multipart/form-data` boundary CVSS 3.1HIGH 7.5
Sources
- CVE-2026-42561 · CVE Program
- CVE-2026-42561 · NVD
- FIRST EPSS
- GHSA-pp6c-gr5w-3c5g · GitHub Advisory Database · CC BY 4.0
- CVE-2026-42561 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences