# CVE-2026-46259: procfs: fix missing RCU protection when reading real_parent in do_task_stat()

> A use-after-free vulnerability in the Linux kernel's procfs allows attackers to potentially execute code or escalate privileges via improper RCU protection.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 3 Jun 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-46259, DEBIAN-CVE-2026-46259, GHSA-vg6r-r7wf-v3q2, ROOT-OS-UBUNTU-2204-CVE-2026-46259, ROOT-OS-UBUNTU-2404-CVE-2026-46259, UBUNTU-CVE-2026-46259

## What is CVE-2026-46259?

CVE-2026-46259 is a high-severity use after free vulnerability in Linux kernel, published on 3 Jun 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:

procfs: fix missing RCU protection when reading real_parent in do_task_stat()

When reading /proc/[pid]/stat, do_task_stat() accesses task->real_parent
without proper RCU protection, which leads to:

  cpu 0                               cpu 1
  -----                               -----
  do_task_stat
    var = task->real_parent
                                      release_task
                                        call_rcu(delayed_put_task_struct)
    task_tgid_nr_ns(var)
      rcu_read_lock   <--- Too late to protect task->real_parent!
      task_pid_ptr    <--- UAF!
      rcu_read_unlock

This patch uses task_ppid_nr_ns() instead of task_tgid_nr_ns() to add
proper RCU protection for accessing task->real_parent.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-46259?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46259?

Apply the vendor's patch.

## Is CVE-2026-46259 being exploited?

There is no known exploitation of CVE-2026-46259 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46259 and fix it if it is affected.

What it is: CVE-2026-46259 is a high-severity use after free vulnerability in Linux kernel, published on 3 Jun 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-2026-46259 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-46259/ (Markdown: https://insights.sbomify.com/CVE-2026-46259/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46259
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46259
- OSV: https://osv.dev/vulnerability/CVE-2026-46259

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46259/
Summaries are generated and may contain mistakes; the official description above is the record.