Description
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.
Metrics
CVSS 3.1 6.5/10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| Kludex | starlette | < 1.0.1 |
| Red Hat | Red Hat AI Inference Server 3.3 | — |
| Red Hat | Red Hat AI Inference Server 3.3 | — |
| 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 OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — |
| Red Hat | Red Hat Satellite 6.17 | — |
| Red Hat | Red Hat Satellite 6.18 | — |
| Red Hat | Red Hat Satellite 6.18 | — |
| Red Hat | Red Hat Satellite 6.18 | — |
| Red Hat | Red Hat Satellite 6.19 | — |
| Red Hat | Red Hat Satellite 6.19 | — |
| Red Hat | Red Hat Satellite 6.19 | — |
| Red Hat | Red Hat Satellite 6.19 | — |
| Red Hat | Exploit Intelligence | — |
| Red Hat | OpenShift Lightspeed | — |
| Red Hat | OpenShift Lightspeed | — |
| Red Hat | Red Hat AI Inference Server | — |
References
- https://badhost.orgMitigation, Third Party Advisory
- https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6Patch
- https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mrVendor Advisory
- https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yamlThird Party Advisory
- https://ostif.org/disclosing-the-badhost-vulnerability-in-starletteMitigation, Third Party Advisory
- https://www.secwest.net/starletteExploit, Mitigation, Third Party Advisory
- https://www.x41-dsec.de/lab/advisories/x41-2026-002-starletteExploit, Mitigation, Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:22992Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:22993Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:23346Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:24866Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:26226Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:30088Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:30089Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:34456Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:34526Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:34532Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:37275Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:43038Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:44696Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:51357Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:60520Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:63337Third Party Advisory
- https://access.redhat.com/security/cve/CVE-2026-48710Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2481742Issue Tracking, Third Party Advisory
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48710.jsonThird Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-48710Third Party Advisory, US Government Resource
- https://www.wiz.io/blog/ai-infrastructure-honeypotExploit, Third Party Advisory
Timeline
- Published
- May 26, 2026
- Last modified
- Oct 1, 2026
- Added to CISA KEV
- Sep 2, 2026
- NVD status
- Analyzed