# CVE-2021-47081: habanalabs/gaudi: Fix a potential use after free in gaudi_memset_device_memory

> A use-after-free vulnerability in the Linux kernel's habanalabs driver allows attackers to potentially execute arbitrary code or escalate privileges.

- **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:** No
- **Published:** 1 Mar 2024
- **Updated:** 5 Aug 2026
- **Also known as:** GHSA-xmvq-5949-6227, UBUNTU-CVE-2021-47081

## What is CVE-2021-47081?

CVE-2021-47081 is a high-severity use after free vulnerability in Linux kernel, published on 1 Mar 2024. 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:

habanalabs/gaudi: Fix a potential use after free in gaudi_memset_device_memory

Our code analyzer reported a uaf.

In gaudi_memset_device_memory, cb is get via hl_cb_kernel_create()
with 2 refcount.
If hl_cs_allocate_job() failed, the execution runs into release_cb
branch. One ref of cb is dropped by hl_cb_put(cb) and could be freed
if other thread also drops one ref. Then cb is used by cb->id later,
which is a potential uaf.

My patch add a variable 'id' to accept the value of cb->id before the
hl_cb_put(cb) is called, to avoid the potential uaf.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2021-47081?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47081?

No fix has been published for CVE-2021-47081 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-47081 being exploited?

There is no known exploitation of CVE-2021-47081 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-2021-47081 and fix it if it is affected.

What it is: CVE-2021-47081 is a high-severity use after free vulnerability in Linux kernel, published on 1 Mar 2024. 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-2021-47081 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-2021-47081/ (Markdown: https://insights.sbomify.com/CVE-2021-47081/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47081
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47081
- OSV: https://osv.dev/vulnerability/CVE-2021-47081

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47081/
Summaries are generated and may contain mistakes; the official description above is the record.