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

Medium severity, CVSS 6.5. Actively exploited: in CISA KEV since 2026-09-02. EPSS: 7.1% chance of exploitation in the next 30 days.

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.

Affected products

• Encode Starlette: from 0.8.3, before 1.0.1 (fixed in 1.0.1)
• Red Hat Ai Inference Server: from 3.3.0, up to and including 3.3.5
• Red Hat Ansible Automation Platform: version 2.6 only; version 2.7 only
• Red Hat Enterprise Linux Ai: version 3.0 only
• Red Hat Migration Toolkit For Applications: before 8.2.0 (fixed in 8.2.0)
• Red Hat Openshift Ai: from 3.3, before 3.3.5 (fixed in 3.3.5); from 3.4, before 3.4.2 (fixed in 3.4.2)
• Red Hat Openshift Lightspeed: affected versions not specified
• Red Hat Satellite: version 6.17 only; version 6.18 only; version 6.19 only

Published 2026-05-26. Last modified 2026-10-01.