# CVE-2020-15436: Use after free in linux kernel

> Local attackers can exploit a use-after-free in the Linux kernel block device code to escalate privileges or cause a denial of service.

- **Severity:** Medium 6.7 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Nov 2020
- **Updated:** 4 Aug 2024
- **Also known as:** A-174737742, ASB-A-174737742, DEBIAN-CVE-2020-15436, GHSA-pcpr-hxm8-3mj4, UBUNTU-CVE-2020-15436

## What is CVE-2020-15436?

CVE-2020-15436 is a medium-severity use after free vulnerability in Linux kernel, published on 23 Nov 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Use-after-free vulnerability in fs/block_dev.c in the Linux kernel before 5.8 allows local users to gain privileges or cause a denial of service by leveraging improper access to a certain error field.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2020-15436?

It affects 19 products.


Products: Broadcom Brocade Fabric Operating System Firmware, Linux kernel, Netapp A250 Firmware, Netapp A700s Firmware, Netapp Aff 500f Firmware, Netapp Aff 8300 Firmware, Netapp Aff 8700 Firmware, Netapp Aff A400 Firmware, Netapp Cloud Backup, Netapp Fabric-Attached Storage A400 Firmware, Netapp Fas 500f Firmware, Netapp Fas 8300 Firmware, Netapp Fas 8700 Firmware, Netapp H410c Firmware, Netapp H610c Firmware, Netapp H610s Firmware, Netapp H615c Firmware, Netapp Solidfire \& Hci Management Node, Netapp Solidfire Baseboard Management Controller Firmware.

## How do I fix CVE-2020-15436?

Upgrade to a fixed version.

## Is CVE-2020-15436 being exploited?

There is no known exploitation of CVE-2020-15436 in the wild and no public exploit code.

Public exploit code:

- https://github.com/Trinadh465/linux-4.19.72_CVE-2020-15436 (github_poc): https://github.com/Trinadh465/linux-4.19.72_CVE-2020-15436

## Other vulnerabilities in Linux kernel

- [CVE-2023-27534](https://insights.sbomify.com/CVE-2023-27534/): Path traversal in https://github.com/curl/curl (high 8.8)
- [CVE-2021-4197](https://insights.sbomify.com/CVE-2021-4197/): Privilege escalation in kernel (high 7.8)
- [CVE-2023-27538](https://insights.sbomify.com/CVE-2023-27538/): Auth bypass in https://github.com/curl/curl (high 7.7)
- [CVE-2021-27218](https://insights.sbomify.com/CVE-2021-27218/): Integer overflow in n/a (high 7.5)
- [CVE-2021-27219](https://insights.sbomify.com/CVE-2021-27219/): Integer overflow in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-15436 and fix it if it is affected.

What it is: CVE-2020-15436 is a medium-severity use after free vulnerability in Linux kernel, published on 23 Nov 2020. 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-2020-15436 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-2020-15436/ (Markdown: https://insights.sbomify.com/CVE-2020-15436/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-15436
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-15436
- OSV: https://osv.dev/vulnerability/CVE-2020-15436

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-15436/
Summaries are generated and may contain mistakes; the official description above is the record.