Litestar: AllowedHostsMiddleware bypasses host validation via client-controlled X-Forwarded-Host header

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-48061: 0.38% estimated exploitation activity in the next 30 days; percentile 31.56 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary AllowedHostsMiddleware trusts the X-Forwarded-Host header as a fallback when the Host header is absent. Since X-Forwarded-Host is a client-controllable header, an attacker can bypass the allowed hosts validation by omitting the Host header and supplying an X-Forwarded-Host header set to a whitelisted domain. This enables host header injection attacks such as password reset poisoning, cache poisoning, and server-side request routing manipulation. Details In AllowedHostsMiddleware.call, the host value used for validation is resolved as follows: https://github.com/litestar-org/litestar/blob/main/litestar/middleware/allowedhosts.py#L68 When Host is absent (e.g., HTTP/1.0 clients, misconfigured proxies, or raw TCP connections), the middleware falls back to X-Forwarded-Host without any verification that the request actually passed through a trusted reverse proxy. An attacker can send a request with no Host header and set X-Forwarded-Host to any whitelisted domain, bypassing the…

Published by the source

10 Jun 2026, 19:12 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:45 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-3qmc-cj7q-62hv

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-3qmc-cj7q-62hv

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# Patch Next advisory brief: CVE-2026-48061

Advisory: Litestar: AllowedHostsMiddleware bypasses host validation via client-controlled X-Forwarded-Host header
IDs: CVE-2026-48061, GHSA-3qmc-cj7q-62hv
Record: https://patchnext.com/advisories/cve-2026-48061 (revision 2, source checked 26 Oct 2026, 13:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: litestar 2.22.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI litestar: affected < 2.22.0; fixed in 2.22.0

## Suggested inspection (read-only)
- `python -m pip show litestar`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on litestar.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-3qmc-cj7q-62hv (OSV record GHSA-3qmc-cj7q-62hv lists affected ranges: PyPI litestar >=0 <2.22.0 (fixed))
- Verified: https://github.com/advisories/GHSA-3qmc-cj7q-62hv (GitHub-reviewed advisory GHSA-3qmc-cj7q-62hv lists affected ranges: PyPI litestar >=0 <2.22.0)

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