Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks
Priority CRITICAL 86Exploited in the wildCWE-444Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Partial Red Hat: 12 fixed, 5 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat.
Summary
Starlette is a lightweight ASGI framework/toolkit. Prior to version 1.0.1, the HTTP `Host` request header was not validated before being used to reconstruct `request.url`. Because the routing algorithm relies on the raw HTTP path while `request.url` is rebuilt from the `Host` header, a malformed header could make `request.url.path` differ from the path that was actually requested. Middleware and endpoints that apply security restrictions based on `request.url` (rather than the raw `scope` path) could therefore be bypassed. Users should upgrade to a version greater than or equal to version 1.0.1, which validates the `Host` header against the grammar of RFC 9112 §3.2 / RFC 3986 §3.2.2 when constructing `request.url` and falls back to `scope["server"]` for malformed values.
Why it matters now
Exploitation Active In CISA KEV since 2026-09-02CISA due date 2026-09-16
EPSS 0.70288 99th percentileScored 2026-11-08
Public exploit Yes 3 exploit referencesTagged by NVD
Fix Partial starlette (Kludex): 1.0.1starlette (PyPI): 1.0.1Red Hat: 27 advisoriesRed Hat: 12 fixed, 5 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Active
- 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 | starlette | before 1.0.1 | 1.0.1 | Patch available | CNA |
| — | starlette (PyPI) | before 1.0.1 | 1.0.1 | Patch available | GHSA-86qp-5c8j-p5mr |
- starlette VendorKludex Affected before 1.0.1 Fixed in 1.0.1 Patch available CNA
- starlette (PyPI) Vendor— Affected before 1.0.1 Fixed in 1.0.1 Patch available GHSA-86qp-5c8j-p5mr
CPE configurations NVD · 11
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:encode:starlette:*:*:*:*:*:python:*:* | 0.8.3 to before 1.0.1 | Vulnerable | encode |
| cpe:2.3:a:redhat:ai_inference_server:*:*:*:*:*:*:*:* | 3.3.0 – 3.3.5 | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:ansible_automation_platform:2.6:-:*:*:*:*:*:* | 2.6 | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:ansible_automation_platform:2.7:-:*:*:*:*:*:* | 2.7 | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:migration_toolkit_for_applications:*:*:*:*:*:*:*:* | before 8.2.0 | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:openshift_ai:*:*:*:*:*:*:*:* | 3.3 to before 3.3.5; 3.4 to before 3.4.2 | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:openshift_lightspeed:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:satellite:6.17:*:*:*:*:*:*:* | 6.17 | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:satellite:6.18:*:*:*:*:*:*:* | 6.18 | Vulnerable | Red Hat |
| cpe:2.3:a:redhat:satellite:6.19:*:*:*:*:*:*:* | 6.19 | Vulnerable | Red Hat |
- cpe:2.3:a:encode:starlette:*:*:*:*:*:python:*:* Versions 0.8.3 to before 1.0.1 Vulnerable ·encode
- cpe:2.3:a:redhat:ai_inference_server:*:*:*:*:*:*:*:* Versions 3.3.0 – 3.3.5 Vulnerable ·Red Hat
- cpe:2.3:a:redhat:ansible_automation_platform:2.6:-:*:*:*:*:*:* Versions 2.6 Vulnerable ·Red Hat
- cpe:2.3:a:redhat:ansible_automation_platform:2.7:-:*:*:*:*:*:* Versions 2.7 Vulnerable ·Red Hat
- cpe:2.3:a:redhat:migration_toolkit_for_applications:*:*:*:*:*:*:*:* Versions before 8.2.0 Vulnerable ·Red Hat
- cpe:2.3:a:redhat:openshift_ai:*:*:*:*:*:*:*:* Versions 3.3 to before 3.3.5; 3.4 to before 3.4.2 Vulnerable ·Red Hat
- cpe:2.3:a:redhat:openshift_lightspeed:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Red Hat
- cpe:2.3:a:redhat:satellite:6.17:*:*:*:*:*:*:* Versions 6.17 Vulnerable ·Red Hat
- cpe:2.3:a:redhat:satellite:6.18:*:*:*:*:*:*:* Versions 6.18 Vulnerable ·Red Hat
- cpe:2.3:a:redhat:satellite:6.19:*:*:*:*:*:*:* Versions 6.19 Vulnerable ·Red Hat
Remediation
- Fix · CNA starlette (Kludex) Fixed in 1.0.1
- Fix · GHSA-86qp-5c8j-p5mr starlette (PyPI) Fixed in 1.0.1 Advisory →
Red Hat 27 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-2026:84734 Released 2026-10-19 · Red Hat rating CriticalRHOAI 3.4.5 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.4 registry.redhat.io/rhoai/odh-ai-gateway-payload-processing-rhel9, registry.redhat.io/rhoai/odh-automl-rhel9, registry.redhat.io/rhoai/odh-autorag-rhel9 +47
- RHSA-2026:76150 Released 2026-10-05 · Red Hat rating ImportantRed Hat Enterprise Linux AI 3.4.5 security update
- Red Hat Enterprise Linux AI 3.4 registry.redhat.io/rhelai3/bootc-aws-cuda-rhel9, registry.redhat.io/rhelai3/bootc-azure-cuda-rhel9, registry.redhat.io/rhelai3/bootc-azure-rocm-rhel9 +3
Show 24 more Red Hat advisories
- RHSA-2026:76149 Released 2026-10-05 · Red Hat rating ImportantRed Hat Enterprise Linux AI 3.4.5 security update
- Red Hat Enterprise Linux AI 3.4 registry.redhat.io/rhelai3/disk-image-cuda-rhel9
- RHSA-2026:73987 Released 2026-09-30 · Red Hat rating CriticalRHOAI 3.3.7 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.3 registry.redhat.io/rhoai/odh-built-in-detector-rhel9, registry.redhat.io/rhoai/odh-dashboard-rhel9, registry.redhat.io/rhoai/odh-data-science-pipelines-argo-argoexec-rhel9 +47
- RHSA-2026:70979 Released 2026-09-23 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (cuda)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-cuda-rhel9
- RHSA-2026:70969 Released 2026-09-23 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (spyre)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-spyre-rhel9
- RHSA-2026:70965 Released 2026-09-23 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (cpu)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-cpu-rhel9
- RHSA-2026:69467 Released 2026-09-21 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (cuda)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-cuda-rhel9
- RHSA-2026:69466 Released 2026-09-21 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (cpu)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-cpu-rhel9
- RHSA-2026:69464 Released 2026-09-21 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (spyre)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-spyre-rhel9
- RHSA-2026:63337 Released 2026-09-03 · 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
- RHSA-2026:60520 Released 2026-08-27 · Red Hat rating CriticalRHOAI 3.4.4 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.4 registry.redhat.io/rhoai/odh-automl-rhel9, registry.redhat.io/rhoai/odh-autorag-rhel9, registry.redhat.io/rhoai/odh-built-in-detector-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-2026:44696 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-2026:37275 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
- RHSA-2026:34532 Released 2026-07-01 · Red Hat rating ModerateGeneral availability of the satellite/iop-host-inventory-rhel9 container image
- Red Hat Satellite 6.19 registry.redhat.io/satellite/iop-host-inventory-rhel9
- RHSA-2026:34526 Released 2026-07-01 · 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-2026:34456 Released 2026-07-01 · Red Hat rating CriticalRHOAI 3.4.2 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.4 registry.redhat.io/rhoai/odh-kserve-storage-initializer-rhel9, registry.redhat.io/rhoai/odh-llama-stack-core-rhel9, registry.redhat.io/rhoai/odh-mlserver-rhel9 +33
- RHSA-2026:30089 Released 2026-06-25 · Red Hat rating CriticalRed Hat AI Inference Server 3.3.5 (CUDA)
- Red Hat AI Inference Server 3.3 registry.redhat.io/rhaiis/vllm-cuda-rhel9
- RHSA-2026:30088 Released 2026-06-25 · Red Hat rating CriticalRed Hat AI Inference Server 3.3.5 (ROCm)
- Red Hat AI Inference Server 3.3 registry.redhat.io/rhaiis/vllm-rocm-rhel9
- RHSA-2026:26226 Released 2026-06-16 · Red Hat rating ImportantGeneral availability of the satellite/iop-host-inventory-rhel9 container image
- Red Hat Satellite 6.18 registry.redhat.io/satellite/iop-host-inventory-rhel9
- RHSA-2026:24866 Released 2026-06-09 · Red Hat rating CriticalRed 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/eda-controller-rhel9, registry.redhat.io/ansible-automation-platform-26/ee-supported-rhel9 +7
- RHSA-2026:23346 Released 2026-06-04 · Red Hat rating CriticalRed Hat Ansible Automation Platform 2.7 Container Release Update
- Red Hat Ansible Automation Platform 2.7 registry.redhat.io/ansible-automation-platform-27/lightspeed-chatbot-rhel9
- RHSA-2026:22993 Released 2026-06-03 · Red Hat rating Importantsatellite/foreman-mcp-server-rhel9 container image available as a Technology Preview
- Red Hat Satellite 6.18 registry.redhat.io/satellite/foreman-mcp-server-rhel9
- RHSA-2026:22992 Released 2026-06-03 · Red Hat rating Lowsatellite/foreman-mcp-server-rhel9 container image available as a Technology Preview
- Red Hat Satellite 6.19 registry.redhat.io/satellite/foreman-mcp-server-rhel9
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| OpenShift Lightspeed | Affected | No fix yet |
| Red Hat AI Inference Server | Affected | No fix yet |
| Red Hat Ansible Automation Platform 2 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet |
| Red Hat AI Inference Server 3.3 | Fixed | RHSA-2026:30088, RHSA-2026:30089 |
| Red Hat AI Inference Server 3.4 | Fixed | RHSA-2026:69464, RHSA-2026:69466, RHSA-2026:69467, RHSA-2026:70965, RHSA-2026:70969, RHSA-2026:70979 |
| Red Hat Ansible Automation Platform 2.6 | Fixed | RHSA-2026:24866 |
| Red Hat Ansible Automation Platform 2.7 | Fixed | RHSA-2026:23346 |
| Red Hat Enterprise Linux AI 3.4 | Fixed | RHSA-2026:76149, RHSA-2026:76150 |
| 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, RHSA-2026:73987 |
| Red Hat OpenShift AI 3.4 | Fixed | RHSA-2026:34456, RHSA-2026:60520, RHSA-2026:84734 |
| Red Hat Satellite 6.17 | Fixed | RHSA-2026:44696 |
| Red Hat Satellite 6.18 | Fixed | RHSA-2026:22993, RHSA-2026:26226, RHSA-2026:51357 |
| Red Hat Satellite 6.19 | Fixed | RHSA-2026:22992, RHSA-2026:34526, RHSA-2026:34532, RHSA-2026:63337 |
Not affected: 11 products
- Exploit Intelligence
- OpenShift Lightspeed
- Red Hat Ansible Automation Platform 2
- Red Hat Ansible Automation Platform 2.6
- Red Hat Ansible Automation Platform 2.7
- Red Hat Enterprise Linux AI 3.4
- 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 OpenShift AI 3.4
Timeline
- 2026-09-02 Added to CISA KEV
- 2026-10-02 Threatist record created from CVE-2026-48710
- 2026-10-03 Alias added: GHSA-86qp-5c8j-p5mr
- 2026-10-06 Fix available: RHSA-2026:76149 · Red Hat
- 2026-10-06 Fix available: RHSA-2026:76150 · Red Hat
- 2026-10-06 Fix available: Red Hat Enterprise Linux AI 3.4 · Red Hat
- 2026-10-07 Fix available: RHSA-2026:73987 · Red Hat
- 2026-10-20 Fix available: RHSA-2026:84734 · Red Hat
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-22 Fix available: RHSA-2026:87410 · Red Hat
- 2026-10-23 Fix available: Red Hat OpenShift AI 2.25 · Red Hat
- 2026-10-25 EPSS moved to the 99th percentile and above
References
Exploit 3
Advisory 25
- https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr
- https://badhost.org
- https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yaml
- https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette
- https://nvd.nist.gov/vuln/detail/CVE-2026-48710
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48710.json
- https://bugzilla.redhat.com/show_bug.cgi?id=2481742
- https://access.redhat.com/security/cve/CVE-2026-48710
- https://access.redhat.com/errata/RHSA-2026:60520
- https://access.redhat.com/errata/RHSA-2026:51357
- https://access.redhat.com/errata/RHSA-2026:44696
- https://access.redhat.com/errata/RHSA-2026:43038
- https://access.redhat.com/errata/RHSA-2026:37275
- https://access.redhat.com/errata/RHSA-2026:34532
- https://access.redhat.com/errata/RHSA-2026:34526
- https://access.redhat.com/errata/RHSA-2026:34456
- https://access.redhat.com/errata/RHSA-2026:30089
- https://access.redhat.com/errata/RHSA-2026:30088
- https://access.redhat.com/errata/RHSA-2026:26226
- https://access.redhat.com/errata/RHSA-2026:24866
- https://access.redhat.com/errata/RHSA-2026:23346
- https://access.redhat.com/errata/RHSA-2026:22993
- https://access.redhat.com/errata/RHSA-2026:22992
- https://access.redhat.com/errata/RHSA-2026:63337
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-48710
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-2026-30841 Python-Multipart: Denial of Service via unbounded multipart part headers 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-2026-48710 · CVE Program
- CVE-2026-48710 · NVD
- CISA Known Exploited Vulnerabilities
- FIRST EPSS
- GHSA-86qp-5c8j-p5mr · GitHub Advisory Database · CC BY 4.0
- CVE-2026-48710 · 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