# CVE-2022-40188: knot-resolver: Knot Resolver before 5.5.3 allows remote attackers to cause a denial of service (CPU consumption) because of algorith...

CVE-2022-40188 is fixed in 3 products on 1 platform, first by knot-resolver 2.1.1-1ubuntu0.1~esm2, released September 23, 2022. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2022-40188
- Priority: High
- CVSS: 7.5 (Medium)
- EPSS: 0.0195
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 23, 2022

## Description

Knot Resolver before 5.5.3 allows remote attackers to cause a denial of service (CPU consumption) because of algorithmic complexity. During an attack, an authoritative server must return large NS sets or address sets.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | knot-resolver Debian 12.15 (bookworm) | 5.5.3-1 | [DEBIAN-CVE-2022-40188](https://patchblox.com/security/data/fix/linux/debian-cve-2022-40188.md) | Sep 23, 2022 |
| Linux | knot-resolver Debian 13.5 (trixie) | 5.5.3-1 | [DEBIAN-CVE-2022-40188](https://patchblox.com/security/data/fix/linux/debian-cve-2022-40188.md) | Sep 23, 2022 |
| Linux | knot-resolver Debian 14 | 5.5.3-1 | [DEBIAN-CVE-2022-40188](https://patchblox.com/security/data/fix/linux/debian-cve-2022-40188.md) | Sep 23, 2022 |
| Linux | knot-resolver Ubuntu 18.04.6 LTS (bionic) | 2.1.1-1ubuntu0.1~esm2 | [knot-resolver 2.1.1-1ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-knot-resolver-2.1.1-1ubuntu0.1-esm2.md) | Sep 23, 2022 |
| Linux | knot-resolver Ubuntu 20.04 LTS (focal) | 3.2.1-3ubuntu2.1 | [knot-resolver 3.2.1-3ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-knot-resolver-3.2.1-3ubuntu2.1.md) | Sep 23, 2022 |
| Linux | knot-resolver Ubuntu 22.04.1 LTS (jammy) | 5.4.4-1ubuntu0.1~esm1 | [knot-resolver 5.4.4-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-knot-resolver-5.4.4-1ubuntu0.1-esm1.md) | Sep 23, 2022 |
| Linux | knot-resolver-module-http Ubuntu 18.04.6 LTS (bionic) | 2.1.1-1ubuntu0.1~esm2 | [knot-resolver-module-http 2.1.1-1ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-knot-resolver-module-http-2.1.1-1ubuntu0.1-esm2.md) | Sep 23, 2022 |
| Linux | knot-resolver-module-http Ubuntu 20.04 LTS (focal) | 3.2.1-3ubuntu2.1 | [knot-resolver-module-http 3.2.1-3ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-knot-resolver-module-http-3.2.1-3ubuntu2.1.md) | Sep 23, 2022 |
| Linux | knot-resolver-module-http Ubuntu 22.04.1 LTS (jammy) | 5.4.4-1ubuntu0.1~esm1 | [knot-resolver-module-http 5.4.4-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-knot-resolver-module-http-5.4.4-1ubuntu0.1-esm1.md) | Sep 23, 2022 |
| Linux | libkres6 Ubuntu 18.04.6 LTS (bionic) | 2.1.1-1ubuntu0.1~esm2 | [libkres6 2.1.1-1ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libkres6-2.1.1-1ubuntu0.1-esm2.md) | Sep 23, 2022 |

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Data as of 2026-11-08T13:06:02Z 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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