To whom it may concern,

We experienced a significant system clock issue on several Debian virtual machines using systemd-timesyncd.

The incident occurred between 2026-10-08 02:26:51 CEST and 2026-10-08 04:42:53 CEST, corresponding to 2026-10-08 00:26:51 UTC and 2026-10-08 02:42:53 UTC.

Environment

  *
Operating system: Debian 14(forky)
  *   Virtualization: QEMU/KVM managed by libvirt
  *   Clock source: kvm-clock
  *   NTP client: systemd-timesyncd

Observed behavior

The affected virtual machines experienced an apparent forward clock jump of approximately 33 days. The machines then operated with the incorrect future date for approximately two hours and sixteen minutes.

Afterward, systemd-timesyncd corrected the clock backward by exactly:

Hi,

although systemd-timesyncd comes preconfigured with NTP server
addresses

0.debian.pool.ntp.org
1.debian.pool.ntp.org
2.debian.pool.ntp.org
3.debian.pool.ntp.org

Debian does not actually operate the NTP servers at those addresses;
they are known as vendor zones[1]. Therefore, debian cannot provide any
information about what could have happened with any specific NTP server.

The history for the NTP server you used shows[2] that something strange
happened at that time. If you want to know more, you need to contact the
person operating that NTP server, not debian.

[1] https://www.ntppool.org/en/vendors.html
[2] https://www.ntppool.org/scores/152.53.239.75