Use of insufficiently random values in AdGuard Home - CVE-2026-47703
Published: May 22, 2026
Vulnerability identifier: #VU132146
CSH Severity: Medium
CVSS v4.0: 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
CVE-ID: CVE-2026-47703
CWE-ID: CWE-330
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: AdGuard
Affected software:
AdGuard Home
AdGuard Home
Detailed vulnerability description
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.
How to mitigate CVE-2026-47703
Install security update from vendor's website.