Vulnerability in Encode Starlette
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.
Vulnerability class: HTTP Request Smuggling
EPSS: 0.110 (95.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
Affected products
- Encode Starlette
- Kludex Starlette — versions < 1.0.1
- Redhat Ai_inference_server
- Redhat Ansible_automation_platform — versions 2.6, 2.7
- Redhat Enterprise_linux_ai — versions 3.0
- Redhat Migration_toolkit_for_applications
- Redhat Openshift_ai
- Redhat Openshift_lightspeed
- Redhat Satellite — versions 6.17, 6.18, 6.19
Weakness classification (CWE)
CISA KEV (Known Exploited Vulnerabilities)
This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.
BOD 22-01 due date: .
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.
Public proof-of-concept exploits
References
- security-advisories@github.com (Third Party Advisory, x_refsource_MISC, Mitigation)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
- security-advisories@github.com (Third Party Advisory, x_refsource_MISC)
- security-advisories@github.com (Third Party Advisory, x_refsource_MISC, Mitigation)
- security-advisories@github.com (Exploit, Third Party Advisory, x_refsource_MISC, Mitigation)
- security-advisories@github.com (Exploit, Third Party Advisory, x_refsource_MISC, Mitigation)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Third Party Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Third Party Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-48710?
- CVE-2026-48710 is a medium-severity vulnerability in Encode Starlette, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 6.5/10. Published 2026-05-26.
- How severe is CVE-2026-48710?
- Medium severity. CVSS v3 base score is 6.5 out of 10.
- Is CVE-2026-48710 known to be exploited?
- Yes. CVE-2026-48710 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-09-02), indicating it is being actively exploited. 5 public proof-of-concept repositories are indexed.