PatchTheCVECVE-2023-26249: Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification attacks and pot
CVE-2023-26249 is a high-severity flaw (CVSS 7.5) affecting knot resolver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- High severity
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.5 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.7% (top 47%) |
| CISA exploited list | No |
| Weakness | CWE-770 |
| Published | 2023-02-21 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2023-26249?
knot resolver: upgrade to 5.6.0. Exact commands for each OS are on this page.
Is CVE-2023-26249 being exploited?
CVE-2023-26249 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2023-26249 affect?
CVE-2023-26249 affects knot resolver. Severity is high (CVSS 7.5). 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 s
How urgent is CVE-2023-26249?
Priority 45/100. High severity; Remotely exploitable, no login, no user action
Related CVEs
- CVE-2023-46317 HIGH 7.5 UPGRADE Knot Resolver before 5.7.0 performs many TCP reconnections upon receiving certain nonsensical responses from s
- CVE-2022-40188 HIGH 7.5 UPGRADE MITIGATE Knot Resolver before 5.5.3 allows remote attackers to cause a denial of service (CPU consumption) because of a
- CVE-2022-32983 MEDIUM 5.3 UPGRADE Knot Resolver through 5.5.1 may allow DNS cache poisoning when there is an attempt to limit forwarding actions
- CVE-2021-40083 HIGH 7.5 UPGRADE Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case
- CVE-2020-12667 HIGH 7.5 UPGRADE Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled s