What’s Vulnerable › Vulnerabilities

CVE-2023-26249

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-02-21 · updated 2026-06-17
• Weakness: CWE-770

Description

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.

Affected products

• CZ.NIC knot-resolver: before 5.6.0 — fixed in 5.6.0

How to fix

Upgrade to a fixed version: CZ.NIC knot-resolver 5.6.0. Check the vendor advisory for mitigations.

References

• https://www.knot-resolver.cz/2023-01-26-knot-resolver-5.6.0.html
• https://www.knot-resolver.cz/2023-01-26-knot-resolver-5.6.0.html

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