Tuomas Räsänen discovered that unsafe signal handling in nbd-server, the server for the Network Block Device protocol, could allow remote attackers to cause a deadlock in the server process and thus a denial of service. Tuomas Räsänen also discovered that the modern-style negotiation was carried out in the main server process before forking the actual client handler. This could allow a remote attacker to cause a denial of service by querying a non-existent export. This issue only affected the oldstable distribution .