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CVE-2026-48710

medium CISA KEV

Kludex Starlette HTTP Request/Response Smuggling Vulnerability

Vendor / product: Kludex — Starlette

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.

CVSS
6.5
6.5 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2026-05-26 22:16
Modified: 2026-10-01 18:17
NVD status: Analyzed
Last synced 1 day ago
Verified against the source API 2026-10-27 07:07 UTC
Exploitation
Listed in CISA KEV
Added 2026-09-02 · due 2026-09-16
Known ransomware use: Unknown

Required action (CISA)

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.

Affected products

encode / starlette ≥0.8.3 <1.0.1
redhat / ai_inference_server ≥3.3.0 ≤3.3.5
redhat / ansible_automation_platform 2.6, 2.7
redhat / migration_toolkit_for_applications <8.2.0
redhat / openshift_ai ≥3.3 <3.3.5, ≥3.4 <3.4.2
redhat / openshift_lightspeed all versions
redhat / satellite 6.17, 6.18, 6.19
redhat / enterprise_linux_ai 3.0

Weakness classification (CWE)

CWE-444 CWE-1289

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr
Patch / mitigation: https://badhost.org
Patch / mitigation: https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6
Patch / mitigation: https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette
Patch / mitigation: https://www.secwest.net/starlette
Patch / mitigation: https://www.x41-dsec.de/lab/advisories/x41-2026-002-starlette

References

Data sources

CISA KEV — fetched 2026-10-27 06:50 UTC · record ↗
NVD CVE API 2.0 — fetched 2026-10-27 07:07 UTC · record ↗

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