CVE-2026-80927 timekeeping: Check the return value of tk_get_aux_ts64 in __do_adjtimex()
A race condition in the Linux kernel timekeeping subsystem allows local attackers to leak uninitialized stack data to userspace.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80927?
CVE-2026-80927 is a vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
timekeeping: Check the return value of tk_get_aux_ts64 in __do_adjtimex()
If the auxiliary clock is disabled during tk_get_aux_ts64() but is enabled before tks->clock_valid is checked, then uninitialized stackdata will be used in the calculations and indirectly leaked to userspace.
The same race window also exists after this change and also for the core timekeeper. But in these cases the only effect would be incorrect adjustments and this is userspace's responsibility to avoid this.
Which versions are affected by CVE-2026-80927?
How do I fix CVE-2026-80927?
Apply the vendor's patch.
Is CVE-2026-80927 being exploited?
There is no known exploitation of CVE-2026-80927 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80927, DEBIAN-CVE-2026-80927, GHSA-g365-rm76-m26c, UBUNTU-CVE-2026-80927.