Hostname spoofing via unvalidated request path
Published Jun 22, 2026 · Updated Jun 22, 2026
URL authority confusion in Kludex Starlette before 1.3.0 allows remote attackers to inject a hostname through a malformed HTTP path. Request.url concatenates the scheme, Host value, and scope path without requiring a leading slash, so reparsing treats text after an at sign as the authority host. Exploitation requires an ASGI server to forward the malformed target and security-sensitive code to read request.url before routing or during error handling; ordinary routing returns 404.
Summary
What happened
URL authority confusion in Kludex Starlette before 1.3.0 allows remote attackers to inject a hostname through a malformed HTTP path. Request.url concatenates the scheme, Host value, and scope path without requiring a leading slash, so reparsing treats text after an at sign as the authority host. Exploitation requires an ASGI server to forward the malformed target and security-sensitive code to read request.url before routing or during error handling; ordinary routing returns 404.
The record
- CVE
- CVE-2026-54282
- Published
- Jun 22, 2026
- Updated
- Jun 22, 2026
- Vendor
- Kludex
- Product
- Starlette
- Classifications
- CWE-706, CWE-20
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 22, 2026CVE publishedPublication date reported by the CVE source.
- Jun 22, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.3.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Malformed request-target demonstrationproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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