Versions mentioned in the description apply to the upstream
Remediation section below for
Ubuntu:18.04 relevant versions.
A flaw was found in the way nettle's RSA decryption functions handled specially crafted ciphertext. An attacker could use this flaw to provide a manipulated ciphertext leading to application crash and denial of service.
nettle to version 3.4.1-0ubuntu0.18.04.1 or higher.