# CVE-2023-22409: Denial of service in Junos OS

> A local authenticated attacker can cause a sustained denial of service on Juniper SRX or MX devices by issuing a CLI command when an inconsistent NAT configuration is present.

- **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:** No
- **Published:** 12 Jan 2023
- **Updated:** 7 Apr 2025
- **Also known as:** GHSA-4xhc-3779-5pc3

## What is CVE-2023-22409?

CVE-2023-22409 is a medium-severity denial of service vulnerability in Juniper Junos, published on 12 Jan 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An Unchecked Input for Loop Condition vulnerability in a NAT library of Juniper Networks Junos OS allows a local authenticated attacker with low privileges to cause a Denial of Service (DoS). When an inconsistent "deterministic NAT" configuration is present on an SRX, or MX with SPC3 and then a specific CLI command is issued the SPC will crash and restart. Repeated execution of this command will lead to a sustained DoS. Such a configuration is characterized by the total number of port blocks being greater than the total number of hosts. An example for such configuration is: [ services nat source pool TEST-POOL address x.x.x.0/32 to x.x.x.15/32 ] [ services nat source pool TEST-POOL port deterministic block-size 1008 ] [ services nat source pool TEST-POOL port deterministic host address y.y.y.0/24] [ services nat source pool TEST-POOL port deterministic include-boundary-addresses] where according to the following calculation: 65536-1024=64512 (number of usable ports per IP address, implicit) 64512/1008=64 (number of port blocks per Nat IP) x.x.x.0/32 to x.x.x.15/32 = 16 (NAT IP addresses available in NAT pool) total port blocks in NAT Pool = 64 blocks per IP * 16 IPs = 1024 Port blocks host address y.y.y.0/24 = 256 hosts (with include-boundary-addresses) If the port block size is configured to be 4032, then the total port blocks are (64512/4032) * 16 = 256 which is equivalent to the total host addresses of 256, and the issue will not be seen. This issue affects Juniper Networks Junos OS on SRX Series, and MX Series with SPC3: All versions prior to 19.4R3-S10; 20.1 version 20.1R1 and later versions; 20.2 versions prior to 20.2R3-S6; 20.3 versions prior to 20.3R3-S6; 20.4 versions prior to 20.4R3-S5; 21.1 versions prior to 21.1R3-S4; 21.2 versions prior to 21.2R3-S3; 21.3 versions prior to 21.3R3-S3; 21.4 versions prior to 21.4R3-S1; 22.1 versions prior to 22.1R2-S2, 22.1R3; 22.2 versions prior to 22.2R2.

Weakness: CWE-1284 (Improper Validation of Specified Quantity in Input)

## Which versions are affected by CVE-2023-22409?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2023-22409?

No fix has been published for CVE-2023-22409 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-22409 being exploited?

There is no known exploitation of CVE-2023-22409 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-2023-22409 and fix it if it is affected.

What it is: CVE-2023-22409 is a medium-severity denial of service vulnerability in Juniper Junos, published on 12 Jan 2023. 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-2023-22409 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-2023-22409/ (Markdown: https://insights.sbomify.com/CVE-2023-22409/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-22409
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-22409
- OSV: https://osv.dev/vulnerability/CVE-2023-22409

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-22409/
Summaries are generated and may contain mistakes; the official description above is the record.