SB2026052276 - Use of insufficiently random values in AdGuard Home

Description

This security bulletin contains information about 1 vulnerability.

1) Use of insufficiently random values (CVE-ID: CVE-2026-47703)

CWE-ID: CWE-330 - Use of Insufficiently Random Values

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to interfere with dns resolution by reducing backend query entropy and exposing a source-port oracle.

The vulnerability exists due to improper entropy generation in the doq-to-udp forwarding path when forwarding client-triggered doq queries to a udp upstream. A remote attacker can trigger crafted queries and use quoted-port icmp behavior to infer the backend udp source port to interfere with dns resolution by reducing backend query entropy and exposing a source-port oracle.

On the tested path, the forwarded backend DNS transaction ID is deterministically set to 0 instead of varying per query.

Remediation

Install update from vendor's website.

References

• https://github.com/AdguardTeam/AdGuardHome/security/advisories/GHSA-xgx4-4h9w-53pv
• https://github.com/AdguardTeam/AdGuardHome/security/advisories