# CVE-2019-20812: Denial of service in n/a

> A flaw in the Linux kernel's packet socket implementation allows local attackers to cause a denial of service via CPU consumption and soft lockups.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 3 Jun 2020
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-20812, GHSA-vqww-4qr9-q8f7, UBUNTU-CVE-2019-20812

## What is CVE-2019-20812?

CVE-2019-20812 is a medium-severity denial of service vulnerability in Linux kernel, published on 3 Jun 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An issue was discovered in the Linux kernel before 5.4.7. The prb_calc_retire_blk_tmo() function in net/packet/af_packet.c can result in a denial of service (CPU consumption and soft lockup) in a certain failure case involving TPACKET_V3, aka CID-b43d1f9f7067.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2019-20812?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2019-20812?

Apply the vendor's patch.

## Is CVE-2019-20812 being exploited?

There is no known exploitation of CVE-2019-20812 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-2019-20812 and fix it if it is affected.

What it is: CVE-2019-20812 is a medium-severity denial of service vulnerability in Linux kernel, published on 3 Jun 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-2019-20812 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-2019-20812/ (Markdown: https://insights.sbomify.com/CVE-2019-20812/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-20812
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-20812
- OSV: https://osv.dev/vulnerability/CVE-2019-20812

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-20812/
Summaries are generated and may contain mistakes; the official description above is the record.