# CVE-2021-0283: Memory corruption in Junos OS

> An attacker can cause a kernel crash and system restart by sending specific packet sequences to the device, resulting in a denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Jul 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-mjmr-9wj5-pjjf

## What is CVE-2021-0283?

CVE-2021-0283 is a high-severity memory corruption vulnerability in Juniper Junos, published on 15 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A buffer overflow vulnerability in the TCP/IP stack of Juniper Networks Junos OS allows an attacker to send specific sequences of packets to the device thereby causing a Denial of Service (DoS). By repeatedly sending these sequences of packets to the device, an attacker can sustain the Denial of Service (DoS) condition. The device will abnormally shut down as a result of these sent packets. A potential indicator of compromise will be the following message in the log files: "eventd[13955]: SYSTEM_ABNORMAL_SHUTDOWN: System abnormally shut down" These issue are only triggered by traffic destined to the device. Transit traffic will not trigger these issues. This issue affects: Juniper Networks Junos OS 12.3 versions prior to 12.3R12-S19; 15.1 versions prior to 15.1R7-S10; 16.1 version 16.1R1 and later versions; 16.2 version 16.2R1 and later versions; 17.1 version 17.1R1 and later versions; 17.2 version 17.2R1 and later versions; 17.3 versions prior to 17.3R3-S12; 17.4 version 17.4R1 and later versions; 18.1 versions prior to 18.1R3-S13; 18.2 version 18.2R1 and later versions; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R2-S9, 18.4R3-S9; 19.1 versions prior to 19.1R3-S6; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R2-S7, 19.3R3-S3; 19.4 versions prior to 19.4R3-S5; 20.1 versions prior to 20.1R2-S2, 20.1R3-S1; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R2-S1, 20.4R3; 21.1 versions prior to 21.1R1-S1, 21.1R2; 21.2 versions prior to 21.2R1-S1, 21.2R2.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2021-0283?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2021-0283?

No fix has been published for CVE-2021-0283 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-0283 being exploited?

There is no known exploitation of CVE-2021-0283 in the wild and no public exploit code.

## Other vulnerabilities in Juniper Junos

- [CVE-2023-36845](https://insights.sbomify.com/CVE-2023-36845/): Juniper Junos OS EX Series and SRX Series PHP External Variable Modification (critical 9.8, exploited in the wild)
- [CVE-2020-1631](https://insights.sbomify.com/CVE-2020-1631/): Juniper Junos OS Path Traversal (high 8.8, exploited in the wild)
- [CVE-2025-21590](https://insights.sbomify.com/CVE-2025-21590/): Juniper Junos OS Improper Isolation or Compartmentalization (medium 6.7, exploited in the wild)
- [CVE-2023-36851](https://insights.sbomify.com/CVE-2023-36851/): Juniper Junos OS SRX Series Missing Authentication for Critical Function (medium 5.3, exploited in the wild)
- [CVE-2023-36844](https://insights.sbomify.com/CVE-2023-36844/): Juniper Junos OS EX Series PHP External Variable Modification (medium 5.3, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-0283 and fix it if it is affected.

What it is: CVE-2021-0283 is a high-severity memory corruption vulnerability in Juniper Junos, published on 15 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-0283 in the wild and no public exploit code.

Affected product: Juniper Junos. 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-2021-0283/ (Markdown: https://insights.sbomify.com/CVE-2021-0283/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-0283
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-0283
- OSV: https://osv.dev/vulnerability/CVE-2021-0283

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-0283/
Summaries are generated and may contain mistakes; the official description above is the record.