Host Header Validation Bypass in Starlette <1.0.1 Leading to Routing Bypass
CVE-2026-48710 Published on May 26, 2026

Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks
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.

Vendor Advisory NVD

Known Exploited Vulnerability

This Kludex Starlette HTTP Request/Response Smuggling Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. 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.

The following remediation steps are recommended / required by September 16, 2026: 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 applicab

Vulnerability Analysis

CVE-2026-48710 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. This vulnerability is known to be actively exploited by threat actors in an automatable fashion. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
LOW
Integrity Impact:
LOW
Availability Impact:
NONE

Weakness Types

What is a HTTP Request Smuggling Vulnerability?

When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.

CVE-2026-48710 has been classified to as a HTTP Request Smuggling vulnerability or weakness.

Improper Validation of Unsafe Equivalence in Input

The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.


Products Associated with CVE-2026-48710

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2026-48710 are published in these products:

Red Hat Ansible Automation Platform
 
Red Hat Openshift Ai
 
Red Hat Openshift
 
Red Hat Satellite
 
Red Hat Exploit Intelligence
 
Red Hat Migration Toolkit Applications
 
Red Hat Openshift Lightspeed
 
Red Hat Ai Inference Server
 
Red Hat Enterprise Linux Ai
 
Oracle
 

Affected Versions

Kludex starlette: Red Hat AI Inference Server 3.3: Red Hat AI Inference Server 3.3: Red Hat Ansible Automation Platform 2.6: Red Hat Ansible Automation Platform 2.7: Red Hat Migration Toolkit for Applications 8.2: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.3: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat OpenShift AI 3.4: Red Hat Satellite 6.17: Red Hat Satellite 6.18: Red Hat Satellite 6.18: Red Hat Satellite 6.18: Red Hat Satellite 6.19: Red Hat Satellite 6.19: Red Hat Satellite 6.19: Red Hat Satellite 6.19: Red Hat Exploit Intelligence: Red Hat OpenShift Lightspeed: Red Hat OpenShift Lightspeed: Red Hat AI Inference Server: Red Hat AI Inference Server: Red Hat AI Inference Server: Red Hat AI Inference Server: Red Hat AI Inference Server: Red Hat AI Inference Server: Red Hat AI Inference Server: Red Hat AI Inference Server: Red Hat AI Inference Server: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI):

Exploit Probability

EPSS
1.84%
Percentile
76.75%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.