# CVE-2020-35513: Denial of service in kernel

> A Linux kernel NFS flaw allows users to cause resource starvation and denial of service via incorrect umask handling during concurrent NFSv4.2 access.

- **Severity:** Medium 4.9 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jan 2021
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-35513, GHSA-7qpq-c35p-wc3c, UBUNTU-CVE-2020-35513

## What is CVE-2020-35513?

CVE-2020-35513 is a medium-severity denial of service vulnerability in Linux kernel, published on 25 Jan 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A flaw incorrect umask during file or directory modification in the Linux kernel NFS (network file system) functionality was found in the way user create and delete object using NFSv4.2 or newer if both simultaneously accessing the NFS by the other process that is not using new NFSv4.2. A user with access to the NFS could use this flaw to starve the resources causing denial of service.

Weakness: CWE-271 (Privilege Dropping / Lowering Errors)

## Which versions are affected by CVE-2020-35513?

It affects 2 products.


Products: Linux kernel, Redhat Enterprise Linux.

## How do I fix CVE-2020-35513?

Apply the vendor's patch.

## Is CVE-2020-35513 being exploited?

There is no known exploitation of CVE-2020-35513 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-2020-35513 and fix it if it is affected.

What it is: CVE-2020-35513 is a medium-severity denial of service vulnerability in Linux kernel, published on 25 Jan 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-35513 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-2020-35513/ (Markdown: https://insights.sbomify.com/CVE-2020-35513/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-35513
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-35513
- OSV: https://osv.dev/vulnerability/CVE-2020-35513

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-35513/
Summaries are generated and may contain mistakes; the official description above is the record.