# CVE-2026-53273: tee: optee: prevent use-after-free when the client exits before the supplicant

> A use-after-free in the Linux kernel's OP-TEE driver allows attackers to execute arbitrary code or escalate privileges when a client exits prematurely.

- **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:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-53273, DEBIAN-CVE-2026-53273, GHSA-q972-3fgv-wchc, ROOT-OS-DEBIAN-11-CVE-2026-53273, ROOT-OS-DEBIAN-12-CVE-2026-53273, ROOT-OS-UBUNTU-2204-CVE-2026-53273, ROOT-OS-UBUNTU-2404-CVE-2026-53273, UBUNTU-CVE-2026-53273

## What is CVE-2026-53273?

CVE-2026-53273 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:

tee: optee: prevent use-after-free when the client exits before the supplicant

Commit 70b0d6b0a199 ("tee: optee: Fix supplicant wait loop") made the
client wait as killable so it can be interrupted during shutdown or
after a supplicant crash. This changes the original lifetime expectations:
the client task can now terminate while the supplicant is still processing
its request.

If the client exits first it removes the request from its queue and
kfree()s it, while the request ID remains in supp->idr. A subsequent
lookup on the supplicant path then dereferences freed memory, leading to
a use-after-free.

Serialise access to the request with supp->mutex:

  * Hold supp->mutex in optee_supp_recv() and optee_supp_send() while
    looking up and touching the request.
  * Let optee_supp_thrd_req() notice that the client has terminated and
    signal optee_supp_send() accordingly.

With these changes the request cannot be freed while the supplicant still
has a reference, eliminating the race.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-53273?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53273?

Apply the vendor's patch.

## Is CVE-2026-53273 being exploited?

There is no known exploitation of CVE-2026-53273 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-2026-53273 and fix it if it is affected.

What it is: CVE-2026-53273 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-2026-53273 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-2026-53273/ (Markdown: https://insights.sbomify.com/CVE-2026-53273/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53273
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53273
- OSV: https://osv.dev/vulnerability/CVE-2026-53273

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53273/
Summaries are generated and may contain mistakes; the official description above is the record.