CVE-2025-58066

nptd-rs is a tool for synchronizing your computer's clock, implementing the NTP and NTS protocols. In versions between 1.2.0 and 1.6.1 inclusive servers which allow non-NTS traffic are affected by a denial of service vulnerability, where an attacker can induce a message storm between two NTP servers running ntpd-rs. Client-only configurations are not affected. Affected users are recommended to upgrade to version 1.6.2 as soon as possible.

nptd-rs is a tool for synchronizing your computer's clock, implementing the NTP and NTS protocols. In versions between 1.2.0 and 1.6.1 inclusive servers which allow non-NTS traffic are affected by a denial of service vulnerability, where an attacker can induce a message storm between two NTP servers running ntpd-rs. Client-only configurations are not affected. Affected users are recommended to upgrade to version 1.6.2 as soon as possible.

# Summary A denial of service vulnerability was discovered in ntpd-rs where an attacker can induce a message storm between two NTP servers running ntpd-rs. # Details Since ntpd-rs version 1.2.0, when configured as a server, incorrectly responded to all NTP messages sent to the server's port with a time reply, including to responses from other servers. As a consequence, a message with a spoofed IP address of another server could cause two servers running ntpd-rs to continually respond to each other, consuming significant amounts of resources. # Impact Any time server running ntpd-rs with version between 1.2.0 and 1.6.1 inclusive which allows non-NTS traffic is affected. Client-only configurations are not affected. Affected users are recommended to upgrade to version 1.6.2 as soon as possible. # Workarounds Should upgrading not be possible, the impact of the issue can be mitigated by: - Whitelisting access to only IP addresses of clients using the server, using the ignore filter method. - Blocking incoming non-request traffic on the NTP server port using a firewall. - Disabling public access to the vulnerable NTP server - Disabling the server functionality by removing any [server] sections from the configuration. # Acknowledgements The ntpd-rs authors thank Eric Sesterhenn from X41 D-Sec GmbH for finding and reporting this issue.

# Summary A denial of service vulnerability was discovered in ntpd-rs where an attacker can induce a message storm between two NTP servers running ntpd-rs. # Details Since ntpd-rs version 1.2.0, when configured as a server, incorrectly responded to all NTP messages sent to the server's port with a time reply, including to responses from other servers. As a consequence, a message with a spoofed IP address of another server could cause two servers running ntpd-rs to continually respond to each other, consuming significant amounts of resources. # Impact Any time server running ntpd-rs with version between 1.2.0 and 1.6.1 inclusive which allows non-NTS traffic is affected. Client-only configurations are not affected. Affected users are recommended to upgrade to version 1.6.2 as soon as possible. # Workarounds Should upgrading not be possible, the impact of the issue can be mitigated by: - Whitelisting access to only IP addresses of clients using the server, using the ignore filter method. - Blocking incoming non-request traffic on the NTP server port using a firewall. - Disabling public access to the vulnerable NTP server - Disabling the server functionality by removing any [server] sections from the configuration. # Acknowledgements The ntpd-rs authors thank Eric Sesterhenn from X41 D-Sec GmbH for finding and reporting this issue.