AdGuard Home: Unauthenticated Access via HTTP/2 Upgrade

Summary

An attacker can bypass authentication in AdGuard Home by sending a specific HTTP request, allowing them to access the system without a login. This is a critical issue, and we recommend updating to the latest version of AdGuard Home to fix it. If you can't update immediately, consider blocking HTTP/2 connections to prevent exploitation.

What to do

Update github.com adguardteam to version 0.107.73.

Affected software

Vendor	Product	Affected versions	Fix available
github.com	adguardteam	<= 0.107.73	0.107.73
adguard	adguardhome	<= 0.107.73	–

Original title

AdGuard Home is a network-wide software for blocking ads and tracking. Prior to 0.107.73, an unauthenticated remote attacker can bypass all authentication in AdGuardHome by sending an HTTP/1.1 requ...

Original description

AdGuard Home is a network-wide software for blocking ads and tracking. Prior to 0.107.73, an unauthenticated remote attacker can bypass all authentication in AdGuardHome by sending an HTTP/1.1 request that requests an upgrade to HTTP/2 cleartext (h2c). Once the upgrade is accepted, the resulting HTTP/2 connection is handled by the inner mux, which has no authentication middleware attached. All subsequent HTTP/2 requests on that connection are processed as fully authenticated, regardless of whether any credentials were provided. This vulnerability is fixed in 0.107.73.

nvd CVSS3.1 9.8

Vulnerability type

CWE-287 Improper Authentication