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

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: yes — in CISA KEV since 2026-09-02
EPSS: 70.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-05-26 · updated 2026-10-01
Weakness: CWE-444

Description

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

Kludex starlette: from 0.8.3 before 1.0.1 — fixed in 1.0.1
Red Hat AI Inference Server: from 3.3.0 through 3.3.5
Red Hat Ansible Automation Platform: 2.6, 2.7
RedHat Enterprise Linux Ai: 3.0
RedHat Migration Toolkit For Applications: before 8.2.0 — fixed in 8.2.0
Red Hat OpenShift AI 2.25: from 3.3 before 3.3.5; from 3.4 before 3.4.2 — fixed in 3.3.5, 3.4.2
Red Hat OpenShift Lightspeed: all versions
Red Hat Satellite 6: 6.17, 6.18, 6.19

How to fix

Upgrade to a fixed version: Kludex starlette 1.0.1; RedHat Migration Toolkit For Applications 8.2.0; Red Hat OpenShift AI 2.25 3.3.5, 3.4.2. Check the vendor advisory for mitigations.

References

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