Status: KEV
| Advisory ID: CVE-2026-48710
Key Details
| CVE | CVE-2026-48710 |
| Vulnerability Name | Kludex Starlette HTTP Request/Response Smuggling Vulnerability |
| CVSS Score / Version | 6.5 (Medium) / CVSS v3.1 |
| Updated | 2026-09-22 |
| CVSS Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N |
| CVSS Prose | attack vector is network; attack complexity is low; privileges required is none; user interaction is none; scope is unchanged; confidentiality impact is low; integrity impact is low; availability impact is none. |
| Affected products | see table below |
| Exploitation status | Listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating confirmed active exploitation. |
| KEV listing | Added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-09-02. |
| Exploitation prediction (EPSS) | 7.06% probability of exploitation in the next 30 days (94% percentile) -- FIRST.org's EPSS model. |
Affected Products, Subsystems & Sectors
| Subsystems | Core Infrastructure, EWS Workstation Delivery/Virtualization |
| Sectors | All Sectors |
What to Know
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.
What to Do
Monitor Kludex, encode, and Red Hat's web pages for any future patch releases. See vendor advisory link below.
References
KEV Required Action