CVE-2026-97905 cpufreq: zero-initialize policy cpumask before sysfs publication
A local attacker can read uninitialized kernel memory via sysfs cpufreq attributes when CONFIG_CPUMASK_OFFSTACK is enabled, potentially leaking sensitive data.
- 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-2026-97905?
CVE-2026-97905 is a vulnerability in Linux, published on 25 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:
cpufreq: zero-initialize policy cpumask before sysfs publication
cpufreq_policy_alloc() allocates policy->cpus with alloc_cpumask_var(), i.e. without __GFP_ZERO, unlike the sibling related_cpus and real_cpus masks. With CONFIG_CPUMASK_OFFSTACK=y the mask is a separate kmalloc_node() allocation, so its bitmap holds whatever the slab allocator left behind:
cpufreq_online() cpufreq_policy_alloc() alloc_cpumask_var(&policy->cpus) /* bitmap is uninitialized */ kobject_init_and_add() /* policy%u/ appears in sysfs */ cpufreq_policy_online() cpumask_copy(policy->cpus, cpumask_of(cpu)) /* first valid value */
This leaves a window in which the sysfs attributes are already reachable while policy->cpus is still garbage. show()/store() gate on policy_is_inactive(), i.e. cpumask_empty(policy->cpus), so a non-zero bitmap makes them run the attribute callbacks on a policy that is not initialized yet.
Fix this by using zalloc_cpumask_var() for policy->cpus.
Which versions are affected by CVE-2026-97905?
How do I fix CVE-2026-97905?
Apply the vendor's patch.
Is CVE-2026-97905 being exploited?
There is no known exploitation of CVE-2026-97905 in the wild and no public exploit code.
Sources
Also known as AZL-104235, BELL-CVE-2026-97905, DEBIAN-CVE-2026-97905, GHSA-p8mx-g9vj-j29m, UBUNTU-CVE-2026-97905.