CVE-2026-48710

CVE-2026-48710 is a medium-severity vulnerability in Encode Starlette with a CVSS 3.x base score of 6.5. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2026-09-02). The underlying weakness is classified as CWE-444.

Key facts

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-48710?
CVE-2026-48710 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-48710 being actively exploited?
Yes. CVE-2026-48710 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-09-02, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2026-48710?
CVE-2026-48710 primarily affects Encode Starlette. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-48710?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2026-48710 have an EU (EUVD) identifier?
Yes. CVE-2026-48710 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32016.
When was CVE-2026-48710 published?
CVE-2026-48710 was published on 2026-05-26 and last updated on 2026-09-04.

References

Affected products (11)

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