# CVE-2021-44733: Use after free in n/a

> A race condition in the Linux kernel TEE subsystem allows attackers to trigger a use-after-free, potentially leading to code execution or privilege escalation.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/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:** 22 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** A-213173524, AZL-7063, DEBIAN-CVE-2021-44733, GHSA-4xqq-q6wp-w8h4, PUB-A-213173524, UBUNTU-CVE-2021-44733

## What is CVE-2021-44733?

CVE-2021-44733 is a high-severity use after free vulnerability in Debian Debian Linux, published on 22 Dec 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A use-after-free exists in drivers/tee/tee_shm.c in the TEE subsystem in the Linux kernel through 5.15.11. This occurs because of a race condition in tee_shm_get_from_id during an attempt to free a shared memory object.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2021-44733?

It affects 12 products.


Products: Debian Debian Linux, Fedoraproject Fedora, Linux kernel, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410c Firmware, Netapp H410s Firmware, Netapp H500e Firmware, Netapp H500s Firmware, Netapp H700e Firmware, Netapp H700s Firmware, Redhat Enterprise Linux.

## How do I fix CVE-2021-44733?

Apply the vendor's patch.

## Is CVE-2021-44733 being exploited?

There is no known exploitation of CVE-2021-44733 in the wild and no public exploit code.

Public exploit code:

- Environment with vulnerable kernel for exploitation of the TEE driver (CVE-2021-44733) (github_poc): https://github.com/pjlantz/optee-qemu

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-44733 and fix it if it is affected.

What it is: CVE-2021-44733 is a high-severity use after free vulnerability in Debian Debian Linux, published on 22 Dec 2021. 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-2021-44733 in the wild and no public exploit code.

Affected product: Debian Debian 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-2021-44733/ (Markdown: https://insights.sbomify.com/CVE-2021-44733/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-44733
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-44733
- OSV: https://osv.dev/vulnerability/CVE-2021-44733

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-44733/
Summaries are generated and may contain mistakes; the official description above is the record.