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.
Published: 2026-05-26
Score: 6.5 Medium
EPSS: 1.4% Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Debian DSA Debian DSA DSA-6302-1 starlette security update
Github GHSA Github GHSA GHSA-86qp-5c8j-p5mr Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks
History

Tue, 16 Jun 2026 13:30:00 +0000


Wed, 03 Jun 2026 02:30:00 +0000

Type Values Removed Values Added
First Time appeared Encode
Encode starlette
CPEs cpe:2.3:a:encode:starlette:*:*:*:*:*:python:*:*
Vendors & Products Encode
Encode starlette

Thu, 28 May 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-1289
References
Metrics threat_severity

None

threat_severity

Important


Wed, 27 May 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 27 May 2026 10:30:00 +0000

Type Values Removed Values Added
First Time appeared Kludex
Kludex starlette
Vendors & Products Kludex
Kludex starlette

Tue, 26 May 2026 22:15:00 +0000

Type Values Removed Values Added
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.
Title Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks
Weaknesses CWE-444
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}


Subscriptions

Encode Starlette
Kludex Starlette
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-29T12:34:16.064Z

Reserved: 2026-05-22T18:47:27.755Z

Link: CVE-2026-48710

cve-icon Vulnrichment

Updated: 2026-06-29T12:34:16.064Z

cve-icon NVD

Status : Modified

Published: 2026-05-26T22:16:44.020

Modified: 2026-06-17T10:55:13.440

Link: CVE-2026-48710

cve-icon Redhat

Severity : Important

Publid Date: 2026-05-26T21:54:54Z

Links: CVE-2026-48710 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-05-28T04:45:07Z

Weaknesses