CVE-2023-26249

Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification...

7.5 HighFix available

Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification attacks and potentially causing a denial of service. Specifically, a single client query may lead to a hundred TCP connection attempts if a DNS server closes connections without providing a response.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

0.71%Down 0.2 points since Feb 21, 2023

What each source reports

NVD Score used 7.5

Record: CVE-2023-26249
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-770
Updated: 2026-11-02

CVE List 7.5

Record: CVE-2023-26249
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-770
Updated: 2026-11-02

EUVDEUVD-2023-30073 7.5

Record: EUVD-2023-30073
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

GitHub AdvisoriesGHSA-38wr-pjxc-vgf7 7.5

Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification...

Record: GHSA-38wr-pjxc-vgf7
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-770
Updated: 2026-11-02

OSV 7.5

Record: CVE-2023-26249
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2023-26249 7.5

Record: DEBIAN-CVE-2023-26249
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2023-26249 7.5

Record: UBUNTU-CVE-2023-26249
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

Affected products

nic knot resolver

Affected packages

Affected packages
Package	Affected	Fixed
`knot-resolver` Debian:12	before 5.6.0-1	5.6.0-1
`knot-resolver` Debian:13	before 5.6.0-1	5.6.0-1
`knot-resolver` Debian:14	before 5.6.0-1	5.6.0-1
`knot-resolver` Ubuntu:Pro:16.04:LTS	All versions, plus listed versions 1.0.0~beta2-123-g6134920-11.0.0~beta3-11.0.0~beta3-1ubuntu0.1~esm1	None known
`knot-resolver` Ubuntu:Pro:18.04:LTS	All versions, plus listed versions 1.3.3-11.5.0-41.5.1-11.5.2-12.0.0-3 Show 4 moreShow less 2.1.0-12.1.0-22.1.1-12.1.1-1ubuntu0.1~esm2	None known
`knot-resolver` Ubuntu:20.04:LTS	All versions, plus listed versions 3.2.1-33.2.1-3ubuntu13.2.1-3ubuntu23.2.1-3ubuntu2.13.2.1-3ubuntu2.2	None known
`knot-resolver` Ubuntu:Pro:22.04:LTS	All versions, plus listed versions 5.3.1-15.4.2-15.4.3-15.4.4-15.4.4-1ubuntu0.1~esm1	None known

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-26249 is a high vulnerability (CVSS 7.5) in Nic Knot Resolver, published February 21, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.71%, the 53rd percentile. Fixed in knot-resolver 5.6.0-1.