CVE-2026-55991 | NLnet Labs Unbound up to 1.25.1 Varint serialization ngtcp2_put_uvarintlen error_code input validation

A vulnerability marked as critical has been reported in NLnet Labs Unbound up to 1.25.1. This affects the function ngtcp2_put_uvarintlen of the component Varint serialization. This manipulation of the argument error_code causes improper input validation.

This vulnerability is handled as CVE-2026-55991. The attack can be initiated remotely. There is not any exploit available.