# CVE-2023-0026: Denial of service in Junos OS

> An unauthenticated remote attacker can cause a sustained Denial of Service by sending specific BGP update messages, affecting Juniper network devices.

- **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:** 21 Jun 2023
- **Updated:** 6 Dec 2024
- **Also known as:** GHSA-fq52-pj3r-g45r

## What is CVE-2023-0026?

CVE-2023-0026 is a high-severity denial of service vulnerability in Juniper Junos, published on 21 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An Improper Input Validation vulnerability in the Routing Protocol Daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network-based attacker to cause a Denial of Service (DoS). When a BGP update message is received over an established BGP session, and that message contains a specific, optional transitive attribute, this session will be torn down with an update message error. This issue cannot propagate beyond an affected system as the processing error occurs as soon as the update is received. This issue is exploitable remotely as the respective attribute can propagate through unaffected systems and intermediate AS (if any). Continuous receipt of a BGP update containing this attribute will create a sustained Denial of Service (DoS) condition. Some customers have experienced these BGP session flaps which prompted Juniper SIRT to release this advisory out of cycle before fixed releases are widely available as there is an effective workaround.

This issue affects:
Juniper Networks Junos OS
15.1R1 and later versions prior to 20.4R3-S8;
21.1 version 21.1R1 and later versions prior to 21.2R3-S6;
21.3 versions prior to 21.3R3-S5;
21.4 versions prior to 21.4R3-S4;
22.1 versions prior to 22.1R3-S4;
22.2 versions prior to 22.2R3-S2;
22.3 versions prior to 22.3R2-S2, 22.3R3-S1;
22.4 versions prior to 22.4R2-S1, 22.4R3;
23.1 versions prior to 23.1R1-S1, 23.1R2.

Juniper Networks Junos OS Evolved
All versions prior to 20.4R3-S8-EVO;
21.1 version 21.1R1-EVO and later versions prior to 21.2R3-S6-EVO;
21.3 versions prior to 21.3R3-S5-EVO;
21.4 versions prior to 21.4R3-S4-EVO;
22.1 versions prior to 22.1R3-S4-EVO;
22.2 versions prior to 22.2R3-S2-EVO;
22.3 versions prior to 22.3R2-S2-EVO, 22.3R3-S1-EVO;
22.4 versions prior to 22.4R2-S1-EVO, 22.4R3-EVO;
23.1 versions prior to 23.1R1-S1-EVO, 23.1R2-EVO.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2023-0026?

It affects 2 products.


Products: Juniper Junos, Juniper Junos Os Evolved.

## How do I fix CVE-2023-0026?

No fix has been published for CVE-2023-0026 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-0026 being exploited?

There is no known exploitation of CVE-2023-0026 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-2023-0026 and fix it if it is affected.

What it is: CVE-2023-0026 is a high-severity denial of service vulnerability in Juniper Junos, published on 21 Jun 2023. 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-2023-0026 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-2023-0026/ (Markdown: https://insights.sbomify.com/CVE-2023-0026/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-0026
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-0026
- OSV: https://osv.dev/vulnerability/CVE-2023-0026

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-0026/
Summaries are generated and may contain mistakes; the official description above is the record.