---
id: "CVE-2026-63183"
kind: "vulnerability"
aliases: ["CVE-2026-63183"]
title: "OmniAuth: forged Host header can redirect login callbacks to attacker hosts"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["omniauth", "package", "rack", "rails", "ruby"]
not_affected_if: ["fixed-full-host", "host-authorization-enabled"]
published_at: "2026-11-04T19:17:40+00:00"
first_seen_at: "2026-11-04T19:28:48+00:00"
updated_at: "2026-11-04T19:30:11+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63183", "first_seen_at": "2026-11-04T19:28:48+00:00"}]
---

# OmniAuth: forged Host header can redirect login callbacks to attacker hosts

OmniAuth builds provider callback URLs from the request's Host header when no fixed full_host or framework host check is set. An unauthenticated remote client can send a forged Host header, which can point login callbacks at an attacker-controlled host.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed version with `bundle exec gem list omniauth` or by reading `omniauth` in `Gemfile.lock`.
- Look for `full_host` set in the OmniAuth configuration.
- Check whether the web framework validates incoming host headers (for example Rails host authorization).

## Fix

- OmniAuth: move to `2.2.0` or later.

## Timeline

- 2026-11-04T19:28:48+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-63183

## Documents

- [advisory] Vendor advisory: github.com https://github.com/omniauth/omniauth/security/advisories/GHSA-m27g-v28p-f9fx
- [fix] Patch: github.com https://github.com/omniauth/omniauth/commit/943b44faea242f063fa9230254fe7d60cfcc9c90

## From the sources

OmniAuth is a flexible authentication system utilizing Rack middleware. Prior to 2.2.0, OmniAuth derives provider callback URLs from request-controlled host information when neither a fixed full_host nor framework-level incoming host validation is configured. A remote unauthenticated client can supply a forged Host header, creating a host header injection risk in applications whose web framework does not verify incoming host headers. Applications using appropriately configured Rails host authorization or a fixed full_host are not affected by this path. This issue is fixed in version 2.2.0.

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