Vulnerability · Published Jun 25, 2026 · Assigned by OX
CVE-2026-42004EDNS options smuggling
Low 3.7
In plain English
A low-severity security flaw in DNSdist from PowerDNS. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)3.7Low
Exploit odds (30 days)0.2%top 86.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
An attacker can send a crafted EDNS OPT record that will be ignored by DNSdist’s filtering rules, but will be rewritten as a valid OPT record when EDNS Client Subnet is inserted, causing the backend to see the EDNS option(s) that DNSdist did not filter.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | dnsdist | no fix listed | DEBIAN-CVE-2026-42004 |
| Debian:13 | dnsdist | 1.9.15-0+deb13u1 | DEBIAN-CVE-2026-42004 |
| Debian:14 | dnsdist | 2.1.0-1 | DEBIAN-CVE-2026-42004 |
| Ubuntu:25.10 | dnsdist | no fix listed | UBUNTU-CVE-2026-42004 |
| Ubuntu:26.04:LTS | dnsdist | no fix listed | UBUNTU-CVE-2026-42004 |
| Ubuntu:26.10 | dnsdist | no fix listed | UBUNTU-CVE-2026-42004 |
Affected products (as reported)
Weakness: CWE-115 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N