# CVE-2026-89765: timers/itimer: Zero-init old itimerval before copy to userspace

> Local attackers can read uninitialized kernel memory via getitimer on sparc64 due to missing zero-initialization of padding bytes.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100623, BELL-CVE-2026-89765, DEBIAN-CVE-2026-89765, GHSA-x38g-mr96-v378, UBUNTU-CVE-2026-89765

## What is CVE-2026-89765?

CVE-2026-89765 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:

timers/itimer: Zero-init old itimerval before copy to userspace

On native sparc64, struct __kernel_old_timeval contains a four-byte hole
after tv_usec because tv_sec is 64-bit while __kernel_suseconds_t is 32-bit.
put_itimerval() fills only the named fields in a stack-allocated
__kernel_old_itimerval and copies the entire object to userspace, so
getitimer() can expose the two padding holes.

Zero-initialize the aggregate before assigning the fields so implicit
padding is deterministic before it crosses the user/kernel boundary.

## Which versions are affected by CVE-2026-89765?


## How do I fix CVE-2026-89765?

Apply the vendor's patch.

## Is CVE-2026-89765 being exploited?

There is no known exploitation of CVE-2026-89765 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89765 and fix it if it is affected.

What it is: CVE-2026-89765 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.
Exploitation: There is no known exploitation of CVE-2026-89765 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-2026-89765/ (Markdown: https://insights.sbomify.com/CVE-2026-89765/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89765
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89765
- OSV: https://osv.dev/vulnerability/CVE-2026-89765

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89765/
Summaries are generated and may contain mistakes; the official description above is the record.