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Fencer Intel
low 3.7

CVE-2026-42004 json

EDNS options smuggling

published 4mo ago modified 14d 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

Is CVE-2026-42004 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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
4mo ago

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-09).

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 Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.