AdGuard Home: DoQ-to-UDP State Reduction and Source-Port Oracle

Exploitation

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

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-47703: 0.14% estimated exploitation activity in the next 30 days; percentile 3.65 (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 This report covers the client-triggered DoQ forwarding path in: - dnsproxy v0.81.2 (adguard/dnsproxy:v0.81.2) - AdGuard Home v0.107.74 (adguard/adguardhome:latest, image version label v0.107.74) The issue was reproduced on 2026-04-25 with the products configured through their documented DoQ listener and plain UDP upstream surfaces. The scope is the internal backend UDP hop created when a DoQ query is forwarded to a udp:// upstream. On that path, the backend DNS ID is not preserved as an independent source of entropy. For both products, the backend observer saw dnsid=0 for every sampled client-triggered query on the tested path. Repeated reruns then showed the same txid=0 behavior and the same positive source-port oracle on every sampled run. A separate quoted-port ICMP oracle distinguished the correct backend UDP source port from a wrong one with a stable, client-visible behavior change. Attached evidence: - dnsproxy oracle path on v0.81.2:…

Published by the source

4 Jun 2026, 19:50 UTC

Last modified by the source

20 Jul 2026, 19:05 UTC

Source last checked

26 Oct 2026, 15:25 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xgx4-4h9w-53pv

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# Patch Next advisory brief: CVE-2026-47703

Advisory: AdGuard Home: DoQ-to-UDP State Reduction and Source-Port Oracle
IDs: CVE-2026-47703, GHSA-xgx4-4h9w-53pv
Record: https://patchnext.com/advisories/cve-2026-47703 (revision 1, source checked 26 Oct 2026, 15:25 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/AdguardTeam/dnsproxy 0.81.3; github.com/AdguardTeam/AdGuardHome 0.107.75. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/AdguardTeam/dnsproxy: affected < 0.81.3; fixed in 0.81.3
- Go github.com/AdguardTeam/AdGuardHome: affected <= 0.107.74; fixed in 0.107.75

## Suggested inspection (read-only)
- Go github.com/AdguardTeam/dnsproxy: check the installed version with your package manager.
- Go github.com/AdguardTeam/AdGuardHome: check the installed version with your package manager.

## 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 github.com/AdguardTeam/dnsproxy, github.com/AdguardTeam/AdGuardHome.
- 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://github.com/advisories/GHSA-xgx4-4h9w-53pv (GitHub-reviewed advisory GHSA-xgx4-4h9w-53pv lists affected ranges: Go github.com/AdguardTeam/AdGuardHome >=0 =0 <0.81.3)

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