# CVE-2026-53262: l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl()

> A use-after-free vulnerability in the Linux kernel L2TP module allows local attackers to achieve code execution or privilege escalation via race conditions.

- **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:** 25 Jun 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-90720, BELL-CVE-2026-53262, DEBIAN-CVE-2026-53262, GHSA-5xjr-h8mp-chfc, ROOT-OS-DEBIAN-11-CVE-2026-53262, ROOT-OS-DEBIAN-12-CVE-2026-53262, ROOT-OS-UBUNTU-2204-CVE-2026-53262, ROOT-OS-UBUNTU-2404-CVE-2026-53262, UBUNTU-CVE-2026-53262

## What is CVE-2026-53262?

CVE-2026-53262 is a high-severity use after free vulnerability in Linux kernel, published on 25 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:

l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl()

pppol2tp_ioctl() read sock->sk->sk_user_data directly without any
locks or reference counting.  If a controllable sleep was induced during
copy_from_user() (e.g. via a userfaultfd page fault sleep), a concurrent
socket close could trigger pppol2tp_session_close() asynchronously.  This
frees the l2tp_session structure via the l2tp_session_del_work workqueue.
Upon resuming, the ioctl thread dereferences the stale session pointer,
resulting in a Use-After-Free (UAF).

Fix this by securely fetching the session reference using the RCU-safe,
refcounted helper pppol2tp_sock_to_session(sk) on entry.  This locks the
session's refcount across the sleep.  We structured the function to exit
via standard err breaks, guaranteeing that l2tp_session_put() is cleanly
called on all return paths to drop the reference.

To preserve existing behavior we validate the session and its magic
signature only for the specific L2TP commands that require it.  This
ensures that generic/unknown ioctls called on an unconnected socket
still return -ENOIOCTLCMD and correctly fall back to generic handlers
(e.g. in sock_do_ioctl()).

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-53262?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53262?

Apply the vendor's patch.

## Is CVE-2026-53262 being exploited?

There is no known exploitation of CVE-2026-53262 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-2026-53262 and fix it if it is affected.

What it is: CVE-2026-53262 is a high-severity use after free vulnerability in Linux kernel, published on 25 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-2026-53262 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-2026-53262/ (Markdown: https://insights.sbomify.com/CVE-2026-53262/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53262
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53262
- OSV: https://osv.dev/vulnerability/CVE-2026-53262

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53262/
Summaries are generated and may contain mistakes; the official description above is the record.