# CVE-2020-1657: Junos OS: SRX Series: An attacker sending spoofed packets to IPSec peers may cause a Denial of Service.

> Attackers can cause a sustained Denial of Service on Juniper SRX devices by sending spoofed packets to IPSec peers before security associations are established.

- **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:** 17 Sep 2024
- **Also known as:** GHSA-x66f-9p5x-42r4

## What is CVE-2020-1657?

CVE-2020-1657 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 SRX Series devices, a vulnerability in the key-management-daemon (kmd) daemon of Juniper Networks Junos OS allows an attacker to spoof packets targeted to IPSec peers before a security association (SA) is established thereby causing a failure to set up the IPSec channel. Sustained receipt of these spoofed packets can cause a sustained Denial of Service (DoS) condition. This issue affects IPv4 and IPv6 implementations. This issue affects Juniper Networks Junos OS on SRX Series: 12.3X48 versions prior to 12.3X48-D90; 15.1X49 versions prior to 15.1X49-D190; 17.4 versions prior to 17.4R2-S9, 17.4R3; 18.1 versions prior to 18.1R3-S9; 18.2 versions prior to 18.2R3; 18.3 versions prior to 18.3R1-S7, 18.3R2-S3, 18.3R3; 18.4 versions prior to 18.4R1-S6, 18.4R2-S3, 18.4R3; 19.1 versions prior to 19.1R1-S4, 19.1R2. This issue does not affect 12.3 or 15.1 releases which are non-SRX Series releases.

Weakness: CWE-408 (Incorrect Behavior Order: Early Amplification)

## Which versions are affected by CVE-2020-1657?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2020-1657?

No fix has been published for CVE-2020-1657 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-1657 being exploited?

There is no known exploitation of CVE-2020-1657 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-2020-1657 and fix it if it is affected.

What it is: CVE-2020-1657 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-2020-1657 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-2020-1657/ (Markdown: https://insights.sbomify.com/CVE-2020-1657/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1657
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1657
- OSV: https://osv.dev/vulnerability/CVE-2020-1657

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-1657/
Summaries are generated and may contain mistakes; the official description above is the record.