StarletteApplication · Encode
CVE-2026-54282
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedStarlette 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIn Starlette versions prior to 1.3.0, the HTTP request path is not validated before reconstructing request.url. When a path doesn't begin with / (e.g., @google.com), the URL re-parsing shifts the authority boundary, making request.url.hostname and request.url.netloc attacker-controlled. Code relying on request.url.hostname instead of the Host header or scope can be misled into trusting attacker-supplied hosts.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
StarletteApplication
< 1.3.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Starlette versionRun `pip show starlette` or import starlette; print(starlette.__version__) to see the installed versionAffected if version is lower than 1.3.0
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Locate code using request.url.hostnameSearch your application source files for patterns like `request.url.hostname`, `url.hostname`, or `.hostname` accessed on request URL objectsAffected if any code reads hostname from request.url rather than from the Host header or ASGI scope
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Test path handling behaviorSend a test request with a path that doesn't begin with /, such as `@example.com`, and inspect what request.url.hostname returns versus the actual Host headerAffected if request.url.hostname reflects the path portion (e.g., @example.com) instead of the actual Host header value
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Verify ASGI scope inspectionCompare the value of `scope['headers']` (Host header) against `request.url.hostname` in your application codeAffected if request.url.hostname differs from the Host header when paths lack a leading slash
You are affected if Starlette version is below 1.3.0 AND your code or any dependency reads request.url.hostname, as this value can be manipulated by attacker-supplied paths not starting with /.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped1.3.0
Upgrade to Starlette version 1.3.0 or later. Review code that reads request.url.hostname to ensure it cannot be manipulated by attacker-supplied paths.
1.3.0
- Upgrade Starlette to version 1.3.0 or later using: pip install starlette>=1.3.0
- Verify the upgrade was successful by checking the installed version: pip show starlette
- Test application behavior with paths not beginning with / (e.g., @example.com) to confirm request.url.hostname is no longer attacker-controlled
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Starlette
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-54282 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-54282 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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