PatchTheCVECVE-2020-12667: Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled s
CVE-2020-12667 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 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an "NXNSAttack" issue. This is triggered by random subdomains in the NSDNAME in NS records.
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 | 2.6% (top 15%) |
| CISA exploited list | No |
| Weakness | CWE-400 |
| Published | 2020-05-19 |
| 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-2020-12667?
knot resolver: upgrade to 5.1.1. Exact commands for each OS are on this page.
Is CVE-2020-12667 being exploited?
CVE-2020-12667 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-2020-12667 affect?
CVE-2020-12667 affects knot resolver. Severity is high (CVSS 7.5). Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an "NXNSAttack" issue. This is triggered by random subdomains in the NSDNAME in NS records.
How urgent is CVE-2020-12667?
Priority 53/100. High severity; Remotely exploitable, no login, no user action
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