CVE-2026-48710
Kludex Starlette HTTP Request/Response Smuggling Vulnerability
IN CISA KEV
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.
- Vendor
- Kludex
- Product
- Starlette
- CVSS 3.1
- 6.5 (medium), scored by NVD (primary)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- CVSS 3.1
- 6.5 (medium), scored by security-advisories@github.comCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- CVSS 3.1
- 6.5 (medium), scored by 0b0ca135-0b70-47e7-9f44-1890c2a1c46cCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- Published
- 2026-05-26
- NVD modified
- 2026-10-01
- NVD status
- Analyzed
CISA KEV
- Date added
- 2026-09-02
- Due date
- 2026-09-16
- Ransomware use
- Unknown
- Required action
- Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
EPSS
7.06% chance of exploitation in the next 30 days (percentile 94th)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
References
- badhost.org (Mitigation, Third Party Advisory)
- github.com (Patch)
- github.com (Vendor Advisory)
- github.com (Third Party Advisory)
- ostif.org (Mitigation, Third Party Advisory)
- access.redhat.com (Third Party Advisory)
- access.redhat.com (Third Party Advisory)
- access.redhat.com (Third Party Advisory)
- access.redhat.com (Third Party Advisory)
- access.redhat.com (Third Party Advisory)
- access.redhat.com (Third Party Advisory)
- access.redhat.com (Third Party Advisory)
Data last updated 18 Oct 2026. Sources: NVD API 2.0, CISA KEV catalog, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.