Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-54282
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 3 Nov 2026, 22:55 UTC · Revision 1
Source evidence
Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname
core-osv · Original sourcePublished 22 Jun 2026, 16:45 UTC
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.
osv:CVE-2026-54282
Complete source record
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"title": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"summary": "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.",
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"modified": "2026-10-28T02:30:32.059448466Z",
"provider": "osv",
"references": [
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"published_at": "2026-06-22T16:45:01.629+00:00"
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