# CVE-2026-48710: 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.

- Web page: https://patchblox.com/security/cve/CVE-2026-48710
- Priority: Patch now
- CVSS: 6.5 (medium)
- EPSS: 0.7029
- CISA KEV: listed Sep 2, 2026, federal due date Sep 16, 2026
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 26, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | python-starlette Fedora 43 | 0.52.1-2.fc43 | [FEDORA-2026-E0F378428E](https://patchblox.com/security/data/fix/linux/fedora-2026-e0f378428e.md) | May 28, 2026 |
| Linux | python-starlette opensuse-leap 16.0 | 0.41.3-160000.3.1 | [OPENSUSE-SU-2026:20975-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20975-1.md) | Jun 17, 2026 |
| Linux | python-starlette sles 16.0 | 0.41.3-160000.3.1 | [SUSE-SU-2026:22151-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22151-1.md) | Jun 17, 2026 |
| Linux | python3-starlette Fedora 43 | 0.52.1-2.fc43 | [FEDORA-2026-E0F378428E](https://patchblox.com/security/data/fix/linux/fedora-2026-e0f378428e.md) | May 28, 2026 |
| Linux | python3-starlette+full Fedora 43 | 0.52.1-2.fc43 | [FEDORA-2026-E0F378428E](https://patchblox.com/security/data/fix/linux/fedora-2026-e0f378428e.md) | May 28, 2026 |
| Linux | starlette Debian 12.15 (bookworm) | 0.26.1-1+deb12u1 | [DEBIAN-CVE-2026-48710](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48710.md) | Jun 24, 2026 |
| Linux | starlette Debian 13.5 (trixie) | 0.46.1-3+deb13u2 | [DEBIAN-CVE-2026-48710](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48710.md) | Jun 24, 2026 |
| Linux | starlette Debian 14 | 1.1.0-1 | [DEBIAN-CVE-2026-48710](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48710.md) | Jun 24, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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