CVE-2021-40083: Nic Knot Resolver

High severity, CVSS 7.5. EPSS: 1.4% chance of exploitation in the next 30 days.

Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).

Affected products

• Nic Knot Resolver: before 5.3.2 (fixed in 5.3.2)

Published 2021-08-25. Last modified 2026-06-17.