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CVE-2026-42004

LOWCVSS 3.7/10EPSS 0.16%

Last modified

CVE-2026-42004 is a low-severity vulnerability rated 3.7/10 on the CVSS scale. 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.. EPSS estimates a 0.16% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
3.7/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Probability
0.16%

5.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-42004?
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.
How severe is CVE-2026-42004?
CVE-2026-42004 has a CVSS score of 3.7/10 (LOW severity). The EPSS model estimates a 0.16% probability of exploitation in the next 30 days.
How do I fix CVE-2026-42004?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-42004?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST