CVE-2026-74670 ipvs: stop estimator after disabled calc phase
A race condition in the Linux kernel IPVS estimator allows out-of-bounds writes during namespace teardown, potentially causing a denial of service.
- 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-2026-74670?
CVE-2026-74670 is a high-severity vulnerability in Linux, published on 22 Aug 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:
ipvs: stop estimator after disabled calc phase
IPVS estimator kthread 0 starts with zeroed chain and tick limits until its initial calculation phase completes. If network namespace teardown clears ipvs->enable during that phase, ip_vs_est_calc_phase() can return without installing positive limits.
The kthread can then continue into its main loop and drain est_temp_list with zero chain_max, tick_max and est_max_count values. Each enqueue consumes one available tick row, but est_count never reaches the zero est_max_count value. After all rows are consumed, the row lookup returns IPVS_EST_NTICKS and ip_vs_enqueue_estimator() writes past the ticks and tick_len arrays.
Exit kthread 0 after the calculation phase if the kthread is stopping or IPVS has been disabled. That keeps temporary estimators from being drained after the limits failed to initialize.
Estimator kthreads can now self-exit before teardown or reload stops kd->task. Keep an extra task reference after creation and release it with kthread_stop_put(), so kd->task remains valid until the stop paths consume that reference.
Which versions are affected by CVE-2026-74670?
How do I fix CVE-2026-74670?
Apply the vendor's patch.
Is CVE-2026-74670 being exploited?
There is no known exploitation of CVE-2026-74670 in the wild and no public exploit code.
Sources
Also known as AZL-97365, BELL-CVE-2026-74670, DEBIAN-CVE-2026-74670, GHSA-98mw-8627-45gg, UBUNTU-CVE-2026-74670.