CVE-2026-48710 Kludex Starlette HTTP Request/Response Smuggling
Attackers can bypass path-based security checks in Starlette applications by sending a malformed Host header that poisons the reconstructed request URL.
- Exploited in the wild
- Since 2 Sep 2026
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-48710?
CVE-2026-48710 is a medium-severity vulnerability in Redhat Satellite, published on 26 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-48710?
3 open source packages ship an affected version, including starlette. It affects 8 products.
| Package | Affected | Fixed in |
|---|---|---|
starlette PyPI | All versions | 1.0.1 |
starlette PyPI | All versions | 1.0.1 |
starlette PyPI | All versions | 1.0.1 |
Linux distribution packages (2)
python-google-adk openSUSE:Tumbleweed | All versions | 2.2.0-1.1 |
python-starlette openSUSE:Tumbleweed | All versions | 1.2.0-1.1 |
Products include Encode Starlette, Redhat Ai Inference Server, Redhat Ansible Automation Platform, Redhat Enterprise Linux Ai, Redhat Migration Toolkit for Applications, Redhat Openshift Ai and 2 more.
How do I fix CVE-2026-48710?
Upgrade starlette to 1.0.1 or later. US federal agencies must fix it by 16 Sep 2026.
Is CVE-2026-48710 being exploited?
Yes. Attackers have exploited CVE-2026-48710 in the wild since at least 2 Sep 2026.
Public exploit code: 1 Nuclei template and 5 proofs of concept on GitHub.
Other vulnerabilities in Redhat Satellite
- CVE-2026-54283 Starlette: request.form() limits silently ignored for application/x-www-form-urlencoded enable DoS
- CVE-2026-48818 Starlette: SSRF and NTLM credential theft via UNC paths in StaticFiles on Windows
- CVE-2023-29159 Starlette has Path Traversal vulnerability in StaticFiles
- CVE-2023-30798 MultipartParser DOS with too many fields or files in Starlette Framework
- CVE-2026-48817 Starlette: Arbitrary HTTP method dispatched to `HTTPEndpoint` attributes via `getattr`
Sources
Also known as CLEANSTART-2026-FT89883, CLSA-2026-1781052728, CLSA-2026-1789648460, DEBIAN-CVE-2026-48710, ECHO-8103-2b4d-a762, GHSA-86qp-5c8j-p5mr and 24 more.