--- id: CVE-2026-48710 title: Starlette is a lightweight ASGI framework/toolkit 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 `… severity: medium cvss: 6.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N' cwe: - CWE-444 - CWE-1289 published: '2026-05-26' updated: '2026-06-29' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48710' references: - url: 'https://badhost.org' label: security-advisories@github.com - url: >- https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6 label: security-advisories@github.com - url: >- https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr label: security-advisories@github.com - url: >- https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yaml label: security-advisories@github.com - url: 'https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette' label: security-advisories@github.com - url: 'https://www.secwest.net/starlette' label: security-advisories@github.com - url: 'https://www.x41-dsec.de/lab/advisories/x41-2026-002-starlette' label: security-advisories@github.com - url: 'https://access.redhat.com/errata/RHSA-2026:22992' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:22993' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:23346' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:24866' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:26226' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:30088' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:30089' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/security/cve/CVE-2026-48710' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2481742' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48710.json label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48710' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-48710' - url: 'https://github.com/Kludex/starlette' - url: 'https://access.redhat.com/errata/RHSA-2026:60520' - url: 'https://access.redhat.com/errata/RHSA-2026:51357' - url: 'https://access.redhat.com/errata/RHSA-2026:44696' - url: 'https://access.redhat.com/errata/RHSA-2026:43038' - url: 'https://access.redhat.com/errata/RHSA-2026:37275' - url: 'https://access.redhat.com/errata/RHSA-2026:34532' - url: 'https://access.redhat.com/errata/RHSA-2026:34526' - url: 'https://access.redhat.com/errata/RHSA-2026:34456' - url: 'https://www.cisa.gov/known-exploited-vulnerabilities-catalog' - url: 'https://access.redhat.com/errata/RHSA-2026:69466' - url: 'https://access.redhat.com/errata/RHSA-2026:69467' - url: 'https://access.redhat.com/errata/RHSA-2026:69464' - url: 'https://access.redhat.com/errata/RHSA-2026:70965' - url: 'https://access.redhat.com/errata/RHSA-2026:70979' - url: 'https://access.redhat.com/errata/RHSA-2026:70969' tags: - nvd - kev - in-the-wild - exploit-available - osv - pip - csaf - vex - red-hat epss: 0.36257 epssPercentile: 0.98413 ingestedAt: '2026-06-29T14:29:18.103Z' kev: true exploited: true kevDateAdded: '2026-09-02' kevDueDate: '2026-09-16' kevRansomware: false exploits: github: 5 githubRepos: - 'https://github.com/eris-ths/supply-chain-guard' - 'https://github.com/xtremebeing/starlette-host-header-lab' - 'https://github.com/Bhanunamikaze/BadHost-CVE-2026-48710-Exploit' nuclei: - CVE-2026-48710 checkedAt: '2026-09-24T07:53:04.828Z' exploitAvailable: true aliases: - GHSA-86qp-5c8j-p5mr - PYSEC-2026-161 - X41-2026-002 ecosystem: pip vendor: starlette product: starlette affected: - starlette < 1.0.1 patched: - starlette 1.0.1 --- ## Overview 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. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Package advisory (CVE-2026-48710) Affected packages: - `starlette < 1.0.1` Patched in: - `starlette 1.0.1` Source: https://osv.dev/vulnerability/GHSA-86qp-5c8j-p5mr ## Vendor advisories - **RHSA-2026:30089** · Red Hat · fixed in: Red Hat AI Inference Server 3.3 · released 2026-06-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:30089) - **RHSA-2026:30088** · Red Hat · fixed in: Red Hat AI Inference Server 3.3 · released 2026-06-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:30088) - **RHSA-2026:69466** · Red Hat · fixed in: Red Hat AI Inference Server 3.4 · released 2026-09-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:69466) - **RHSA-2026:69467** · Red Hat · fixed in: Red Hat AI Inference Server 3.4 · released 2026-09-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:69467) - **RHSA-2026:69464** · Red Hat · fixed in: Red Hat AI Inference Server 3.4 · released 2026-09-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:69464) - **RHSA-2026:24866** · Red Hat · fixed in: Red Hat Ansible Automation Platform 2.6 · released 2026-06-09 · [advisory](https://access.redhat.com/errata/RHSA-2026:24866) - **RHSA-2026:23346** · Red Hat · fixed in: Red Hat Ansible Automation Platform 2.7 · released 2026-06-04 · [advisory](https://access.redhat.com/errata/RHSA-2026:23346) - **RHSA-2026:43038** · Red Hat · fixed in: Red Hat Migration Toolkit for Applications 8.2 · released 2026-07-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:43038) - **RHSA-2026:37275** · Red Hat · fixed in: Red Hat OpenShift AI 3.3 · released 2026-07-09 · [advisory](https://access.redhat.com/errata/RHSA-2026:37275) - **RHSA-2026:60520** · Red Hat · fixed in: Red Hat OpenShift AI 3.4 · released 2026-08-27 · [advisory](https://access.redhat.com/errata/RHSA-2026:60520) - **RHSA-2026:34456** · Red Hat · fixed in: Red Hat OpenShift AI 3.4 · released 2026-07-01 · [advisory](https://access.redhat.com/errata/RHSA-2026:34456) - **Red Hat VEX** · Moderate · affected: Exploit Intelligence, OpenShift Lightspeed, Red Hat AI Inference Server, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · no fix planned: Exploit Intelligence, Red Hat AI Inference Server, OpenShift Lightspeed, Red Hat Enterprise Linux AI (RHEL AI) 3, … · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48710.json) - **RHSA-2026:70965** · Red Hat · fixed in: Red Hat AI Inference Server 3.4 · released 2026-09-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:70965) - **RHSA-2026:70979** · Red Hat · fixed in: Red Hat AI Inference Server 3.4 · released 2026-09-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:70979) - **RHSA-2026:70969** · Red Hat · fixed in: Red Hat AI Inference Server 3.4 · released 2026-09-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:70969)