CVE-2026-32136
Authentication Bypass via HTTP/2 Upgrade in AdGuard Home
Publication date: 2026-03-11
Last updated on: 2026-03-13
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| adguard | adguardhome | to 0.107.73 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-287 | When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in AdGuard Home versions prior to 0.107.73. An unauthenticated remote attacker can bypass all authentication by sending an HTTP/1.1 request that requests an upgrade to HTTP/2 cleartext (h2c). When the upgrade is accepted, the HTTP/2 connection is handled by an internal multiplexer that lacks authentication checks. As a result, all subsequent HTTP/2 requests on that connection are treated as fully authenticated, even if no credentials were provided.
How can this vulnerability impact me? :
This vulnerability can have severe impacts because it allows an attacker to gain full authenticated access remotely without any credentials. The attacker can potentially control or manipulate the AdGuard Home service, leading to unauthorized access to network-wide ad blocking and tracking configurations. Given the CVSS score of 9.8, the impact includes high confidentiality, integrity, and availability risks.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade AdGuard Home to version 0.107.73 or later, where the issue is fixed.