# CVE-2020-1683: Junos OS: Memory leak leads to kernel crash (vmcore) due to SNMP polling

> Attackers can cause a kernel crash and service outage on Juniper Junos devices by triggering a memory leak via specific SNMP polling.

- **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:** 16 Oct 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-h8g9-274c-2qqg

## What is CVE-2020-1683?

CVE-2020-1683 is a high-severity denial of service vulnerability in Juniper Junos, published on 16 Oct 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

On Juniper Networks Junos OS devices, a specific SNMP OID poll causes a memory leak which over time leads to a kernel crash (vmcore). Prior to the kernel crash other processes might be impacted, such as failure to establish SSH connection to the device. The administrator can monitor the output of the following command to check if there is memory leak caused by this issue: user@device> show system virtual-memory | match "pfe_ipc|kmem" pfe_ipc 147 5K - 164352 16,32,64,8192 <-- increasing vm.kmem_map_free: 127246336 <-- decreasing pfe_ipc 0 0K - 18598 32,8192 vm.kmem_map_free: 134582272 This issue affects Juniper Networks Junos OS: 17.4R3; 18.1 version 18.1R3-S5 and later versions prior to 18.1R3-S10; 18.2 version 18.2R3 and later versions prior to 18.2R3-S3; 18.2X75 version 18.2X75-D420, 18.2X75-D50 and later versions prior to 18.2X75-D430, 18.2X75-D53, 18.2X75-D60; 18.3 version 18.3R3 and later versions prior to 18.3R3-S2; 18.4 version 18.4R1-S4, 18.4R2 and later versions prior to 18.4R2-S5, 18.4R3-S1; 19.1 version 19.1R2 and later versions prior to 19.1R2-S2, 19.1R3; 19.2 version 19.2R1 and later versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S5, 19.3R3; 19.4 versions prior to 19.4R1-S3, 19.4R2. This issue does not affect Juniper Networks Junos OS prior to 17.4R3.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2020-1683?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2020-1683?

No fix has been published for CVE-2020-1683 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-1683 being exploited?

There is no known exploitation of CVE-2020-1683 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-2020-1683 and fix it if it is affected.

What it is: CVE-2020-1683 is a high-severity denial of service vulnerability in Juniper Junos, published on 16 Oct 2020. 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-2020-1683 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-2020-1683/ (Markdown: https://insights.sbomify.com/CVE-2020-1683/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1683
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1683
- OSV: https://osv.dev/vulnerability/CVE-2020-1683

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-1683/
Summaries are generated and may contain mistakes; the official description above is the record.