CVE-2026-48710: Kludex Starlette

What is CVE-2026-48710?

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.

CVSS6.5 NVD 3.1

SeverityMEDIUM

Exploitation In the wild In CISA KEV

EPSS11% · P96

Triage statusActive Exploit

ActionPatch immediately

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

CWECWE-444, CWE-1289

NVD published2026-05-26

NVD last modified2026-09-03

Timeline

2026-05-26Published to the U.S. National Vulnerability Database (NVD)
2026-09-02Added to the CISA Known Exploited Vulnerabilities (KEV) catalog
2026-09-03NVD record last updated
2026-09-16CISA federal remediation deadline (BOD 22-01)

CISA Known Exploited Vulnerability

Kludex Starlette HTTP Request/Response Smuggling Vulnerability

Added to KEV2026-09-02

Federal patch deadline2026-09-16

Known ransomware useUnknown

Affected product

Kludex Starlette

NVD also lists CPE entries for: Redhat Ai Inference Server, Redhat Ansible Automation Platform, Redhat Migration Toolkit For Applications, Redhat Openshift Ai, Redhat Openshift Lightspeed

Remediation Steps

Apply the vendor security update for Kludex Starlette as a priority.
Restrict network exposure of the affected service to trusted sources until patched.
Review logs and detections for indicators of exploitation.
Confirm fixed versions against the official vendor advisory before deploying.

References

Referenced in our briefings & reports

Vulnerability Priority Report – Week 5 of August 2026 (August 31 – September 6)

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🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.