CVE-2026-54282

Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname

Published Jun 22, 2026 CVSS 3.1 · 3.7 Low EPSS < 1% KEV · Not listed
Description
Starlette is a lightweight ASGI framework/toolkit. Prior to 1.3.0, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host. This vulnerability is fixed in 1.3.0.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4711-1 starlette security update
Debian DSA Debian DSA DSA-6478-1 starlette security update
Github GHSA Github GHSA GHSA-jp82-jpqv-5vv3 Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname
History
Type Values Removed Values Added
First Time appeared Kludex
Kludex starlette
Vendors & Products Kludex
Kludex starlette
Type Values Removed Values Added
Metrics ssvc

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

Type Values Removed Values Added
Description Starlette is a lightweight ASGI framework/toolkit. Prior to 1.3.0, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host. This vulnerability is fixed in 1.3.0.
Title Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname
Weaknesses CWE-706
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 22, 2026, 5:26 PM
Reserved
Jun 12, 2026, 5:46 PM
Status
Analyzed
Published
Jun 22, 2026, 6:16 PM
Modified
Oct 25, 2026, 11:10 PM
Severity
Low
Public date
Jun 22, 2026, 4:45 PM