CVE-2026-48710Kludex Starlette HTTP Request/Response Smuggling Vulnerability

BOD 26-04 remediation window

With CISA's SSVC answers for this CVE (automatable: yes, technical impact: partial), BOD 26-04 Table 1 gives 3 days on a publicly exposed asset (row 2) and 14 days on an asset that is not publicly exposed (row 10) ^S06. CISA set the catalogue due date at 14 days; under BOD 26-04 it reflects CISA's own view of whether the flaw sits on publicly exposed assets ^S07. The directive binds US federal civilian executive branch agencies only.

What CISA says

Short description

Kludex Starlette contains a HTTP request/response smuggling vulnerability that could allow attackers to inject paths into the host part, prepending the actual path leading to issues such as authentication bypass when the authentication depends on the reconstructed URL’s path. This vulnerability could be chaned with CVE-2026-42271.

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.

Notes

This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-48710

CWE in the catalogue

CWE-444

Official links

• CISA KEV catalogue entry cisa.gov
• NVD record nvd.nist.gov

Vendor advisory and patch links

References NVD tags Vendor Advisory or Patch, exactly as NVD lists them.

• https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6 Patch
• https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr Vendor Advisory

Links in CISA's notes

• https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr
• https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
• https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
• https://nvd.nist.gov/vuln/detail/CVE-2026-48710

NVD details

CWE (NVD)

CWE-444 by security-advisories@github.com, CWE-1289 by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS versions in NVD

V31

Last modified in NVD

2026-10-01T18:17:18.153

Where each value comes from

This product uses data from the NVD API but is not endorsed or certified by the NVD. CISA does not endorse Sysprobs. Methodology.