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Fencer Vulns
low 3.7

CVE-2026-42004 json

EDNS options smuggling

published 2026-06-25 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-39351

cvss
3.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

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.

Patch / fix

  • PowerDNS DNSdist 1.9.15, 2.0.7
  • dnsdist Debian 13 1.9.15-0+deb13u1
  • dnsdist Debian 14 2.1.0-1

debian advisories DEBIAN-CVE-2026-42004

  • dnsdist SLES 16.0, SLES for SAP applications 16.0 1.9.15-160000.1.1

suse advisories SUSE-SU-2026:23123-1SUSE-SU-2026:23146-1

  • dnsdist openSUSE Leap 16.0 1.9.15-160000.1.1
  • dnsdist openSUSE Tumbleweed 2.0.7-1.1

opensuse advisories openSUSE-SU-2026:21533-1openSUSE-SU-2026:11411-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-42004 updated cvss 5.3

dnsdist: EDNS options smuggling

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

  • PowerDNS DNSdist

Classification

Weakness
  • CWE-115 Misinterpretation of Input

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.