CVE-2026-42004: Misinterpretation of Input in PowerDNS DNSdist
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.
AI Analysis
Technical Summary
This vulnerability involves DNSdist misinterpreting crafted EDNS OPT records. The filtering mechanism ignores certain crafted EDNS OPT records, but when DNSdist inserts EDNS Client Subnet information, it rewrites these records into valid OPT records. This results in backend servers receiving EDNS options that DNSdist was supposed to filter out, potentially allowing unintended EDNS options to pass through the filtering layer.
Potential Impact
The impact is limited to the integrity of EDNS option filtering in DNSdist. There is no confidentiality or availability impact reported. The backend may receive EDNS options that were intended to be blocked, which could affect downstream processing or policy enforcement relying on filtered EDNS options. The CVSS score of 3.7 reflects a low severity with no direct confidentiality or availability impact and requiring network attack with high complexity.
Mitigation Recommendations
No official patch or remediation level is provided in the available data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, users should be aware of this filtering bypass and consider additional monitoring or compensating controls if EDNS option filtering is critical to their security posture.
CVE-2026-42004: Misinterpretation of Input in PowerDNS DNSdist
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.
CVSS v3.1
Score 3.7low
Affected software
pkg:github/dnsdistRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves DNSdist misinterpreting crafted EDNS OPT records. The filtering mechanism ignores certain crafted EDNS OPT records, but when DNSdist inserts EDNS Client Subnet information, it rewrites these records into valid OPT records. This results in backend servers receiving EDNS options that DNSdist was supposed to filter out, potentially allowing unintended EDNS options to pass through the filtering layer.
Potential Impact
The impact is limited to the integrity of EDNS option filtering in DNSdist. There is no confidentiality or availability impact reported. The backend may receive EDNS options that were intended to be blocked, which could affect downstream processing or policy enforcement relying on filtered EDNS options. The CVSS score of 3.7 reflects a low severity with no direct confidentiality or availability impact and requiring network attack with high complexity.
Mitigation Recommendations
No official patch or remediation level is provided in the available data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, users should be aware of this filtering bypass and consider additional monitoring or compensating controls if EDNS option filtering is critical to their security posture.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- OX
- Date Reserved
- 2026-04-23T11:15:21.198Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a3d2a1b4853345fc1f848ff
Added to database: 06/25/2026, 13:16:11 UTC
Last enriched: 06/25/2026, 13:31:04 UTC
Last updated: 08/09/2026, 12:41:10 UTC
Views: 71
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