starlette: Starlette is a lightweight ASGI framework/toolkit
CVE-2026-48710 is fixed in 4 products on 1 platform, first by FEDORA-2026-E0F378428E, released May 28, 2026. It is being exploited: CISA added it to the Known Exploited Vulnerabilities catalog on September 2, 2026. Patch Radar priority: Patch now.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| python-starlette · Fedora 43 | 0.52.1-2.fc43 | FEDORA-2026-E0F378428E | May 28, 2026 |
| python-starlette · opensuse-leap 16.0 | 0.41.3-160000.3.1 | OPENSUSE-SU-2026:20975-1 | Jun 17, 2026 |
| python-starlette · sles 16.0 | 0.41.3-160000.3.1 | SUSE-SU-2026:22151-1 | Jun 17, 2026 |
| python3-starlette · Fedora 43 | 0.52.1-2.fc43 | FEDORA-2026-E0F378428E | May 28, 2026 |
| python3-starlette+full · Fedora 43 | 0.52.1-2.fc43 | FEDORA-2026-E0F378428E | May 28, 2026 |
| starlette · Debian 12.15 (bookworm) | 0.26.1-1+deb12u1 | DEBIAN-CVE-2026-48710 | Jun 24, 2026 |
| starlette · Debian 13.5 (trixie) | 0.46.1-3+deb13u2 | DEBIAN-CVE-2026-48710 | Jun 24, 2026 |
| starlette · Debian 14 | 1.1.0-1 | DEBIAN-CVE-2026-48710 | Jun 24, 2026 |
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