# CVE-2026-47703: AdGuard Home DNS state reduction and source-port oracle in DoQ forwarding

Source: https://junglewise.ai/threats/cve-2026-47703-adguard-home-dns-state-reduction-and-source-port-oracle-in-doq  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-15. Updated: 2026-07-15  
License: CC BY 4.0 with a link back

CVE-2026-47703 · Severity: medium · CVSS 4 · Published 2026-07-15

AdGuard Home is a network-wide tool used to block advertisements and tracking by managing DNS traffic. A vulnerability in how it handles certain encrypted DNS requests (DNS-over-QUIC) makes it easier for an attacker to predict or manipulate DNS responses. This could potentially allow an attacker to redirect users to malicious websites or disrupt internet connectivity by spoofing DNS data.

Technologies: [github.com/AdguardTeam/AdGuardHome (Go)](https://junglewise.ai/threats/technologies/github-com-adguardteam-adguardhome). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-47703 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-47703 being exploited in the wild.

**How severe is CVE-2026-47703?** Medium severity, with a CVSS score of 4, published 15 July 2026.

**Which products and versions are affected?** AdGuard Team AdGuard Home <= 0.107.74; AdGuard Team Dnsproxy < 0.81.3; github.com/AdguardTeam/AdGuardHome (Go) <= 0.107.74, SEMVER:introduced=0,fixed=0.107.75; github.com/AdguardTeam/dnsproxy (Go) < 0.81.3, SEMVER:introduced=0,fixed=0.81.3.

**Is there a fix for CVE-2026-47703?** Yes. github.com/AdguardTeam/AdGuardHome (Go): upgrade to 0.107.75 or later; github.com/AdguardTeam/dnsproxy (Go): upgrade to 0.81.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-47703 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-47703?** Check whether you run AdGuard Team AdGuard Home, AdGuard Team Dnsproxy, github.com/AdguardTeam/AdGuardHome (Go) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/AdguardTeam/AdGuardHome (Go): upgrade to 0.107.75 or later

  ```sh
  go get github.com/AdguardTeam/AdGuardHome@v0.107.75
  ```

- github.com/AdguardTeam/dnsproxy (Go): upgrade to 0.81.3 or later

  ```sh
  go get github.com/AdguardTeam/dnsproxy@v0.81.3
  ```


## Technical details

A vulnerability exists in the client-triggered DNS-over-QUIC (DoQ) forwarding path to UDP upstreams in AdGuard Home (prior to 0.107.75) and dnsproxy (prior to 0.81.2). The backend DNS transaction ID (txid) is not properly randomized and instead collapses to a deterministic value of 0. Additionally, the implementation exposes a source-port oracle via ICMP error messages, allowing an attacker to identify the backend UDP source port. By reducing the entropy of the (txid, source-port) tuple to just the source port, the software becomes significantly more susceptible to off-path DNS cache poisoning and forgery attacks similar to 'SAD DNS'.

## Affected products

- AdguardTeam AdGuard Home < 0.107.75
- AdguardTeam dnsproxy < 0.81.2

## Identifiers

- CVE-2026-47703
- GHSA-xgx4-4h9w-53pv
- GO-2026-5756

## Timeline

- 2026-04-25: other: Vulnerability reproduced by researchers
- 2026-05-19: advisory: GitHub Security Advisory published
- 2026-07-15: disclosed: CVE-2026-47703 published to NVD

## References

- [https://github.com/AdguardTeam/AdGuardHome/security/advisories/GHSA-xgx4-4h9w-53pv](https://github.com/AdguardTeam/AdGuardHome/security/advisories/GHSA-xgx4-4h9w-53pv)

## Related threats

- [GO-2026-4686 - AdGuard Home: HTTP/2 Cleartext (h2c) Upgrade Authentication Bypass in github.com/AdguardTeam/AdGuardHome](https://junglewise.ai/threats/cve-2026-32136-adguard-home-http-2-cleartext-h2c-upgrade-authentication-bypass)
- [GO-2024-3184 - Adguard Home arbitrary file read vulnerability in github.com/AdguardTeam/AdGuardHome](https://junglewise.ai/threats/cve-2024-36814-adguard-home-arbitrary-file-read-vulnerability)
- [GO-2024-2924 - AdGuardHome privilege escalation vulnerability in github.com/AdguardTeam/AdGuardHome](https://junglewise.ai/threats/cve-2024-36586-adguardhome-privilege-escalation-vulnerability)
- [AdGuardHome vulnerable to Cross-Site Request Forgery](https://junglewise.ai/threats/cve-2022-32175-adguardhome-vulnerable-to-cross-site-request-forgery)