# CVE-2026-42004: dnsdist: An attacker can send a crafted EDNS OPT record that will be ignored by DNSdist’s filtering rules, but will be rewritt...

CVE-2026-42004 is fixed in dnsdist on 1 platform, first by DEBIAN-CVE-2026-42004, released June 26, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-42004
- Priority: Routine
- CVSS: 3.7 (low)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 25, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | dnsdist Debian 13.5 (trixie) | 1.9.15-0+deb13u1 | [DEBIAN-CVE-2026-42004](https://patchblox.com/security/data/fix/linux/debian-cve-2026-42004.md) | Jun 26, 2026 |
| Linux | dnsdist Debian 14 | 2.1.0-1 | [DEBIAN-CVE-2026-42004](https://patchblox.com/security/data/fix/linux/debian-cve-2026-42004.md) | Jun 26, 2026 |
| Linux | dnsdist opensuse-leap 16.0 | 1.9.15-160000.1.1 | [OPENSUSE-SU-2026:21533-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21533-1.md) | Aug 5, 2026 |
| Linux | dnsdist sles 16.0 | 1.9.15-160000.1.1 | [SUSE-SU-2026:23146-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-23146-1.md) | Aug 5, 2026 |

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Data as of 2026-11-07T18:46:35Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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