# 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.

- **Severity:** Not scored
- **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:** Yes
- **Published:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-104235, BELL-CVE-2026-97905, DEBIAN-CVE-2026-97905, GHSA-p8mx-g9vj-j29m, UBUNTU-CVE-2026-97905

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97905 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-97905 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-97905/ (Markdown: https://insights.sbomify.com/CVE-2026-97905/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97905
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97905
- OSV: https://osv.dev/vulnerability/CVE-2026-97905

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97905/
Summaries are generated and may contain mistakes; the official description above is the record.