# CVE-2025-21600: Denial of service in Junos OS

> An unauthenticated BGP peer can cause a denial of service by sending malformed packets to Junos OS systems with specific BGP options enabled.

- **Severity:** High 7.1 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:N/R:A/V:C/RE:M/U:Green`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Jan 2025
- **Updated:** 27 Jan 2025
- **Also known as:** GHSA-p52f-fg64-jqxw

## What is CVE-2025-21600?

CVE-2025-21600 is a high-severity denial of service vulnerability in Juniper Junos, published on 9 Jan 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An Out-of-Bounds Read vulnerability in

the routing protocol daemon (rpd) of 

 Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, logically adjacent BGP peer sending a specifically malformed BGP packet to cause rpd to crash and restart, resulting in a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition.

This issue only affects systems configured in
      either of two ways:

    
    
        *  systems with BGP traceoptions enabled

        *  systems with BGP family traffic-engineering (BGP-LS)
          configured

 and can be exploited from a directly connected and configured BGP peer. 

This issue affects iBGP and eBGP 

with 

any address family

 configured, and both IPv4 and IPv6 are affected by this vulnerability.

This issue affects:

Junos OS: 

  *  

from 21.4 before 21.4R3-S9, 
  *  from 22.2 before 22.2R3-S5, 
  *  from 22.3 before 22.3R3-S4, 
  *  from 22.4 before 22.4R3-S5, 
  *  from 23.2 before 23.2R2-S3, 
  *  from 23.4 before 23.4R2-S3, 
  *  from 24.2 before 24.2R1-S2, 24.2R2; 

Junos OS Evolved: 

  *  from 21.4-EVO before 21.4R3-S9-EVO, 
  *  from 22.2-EVO before 22.2R3-S5-EVO, 
  *  from 22.3-EVO before 22.3R3-S4-EVO, 
  *  from 22.4-EVO before 22.4R3-S5-EVO, 
  *  from 23.2-EVO before 23.2R2-S3-EVO, 
  *  from 23.4-EVO before 23.4R2-S2-EVO, 
  *  from 24.2-EVO before 24.2R1-S2-EVO, 24.2R2-EVO.

This issue does not affect versions of Junos OS prior to 21.3R1.

This issue does not affect versions of Junos OS Evolved prior to 21.3R1-EVO.

This is a similar, but different vulnerability than the issue reported as CVE-2024-39516.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2025-21600?

It affects 2 products.


Products: Juniper Junos, Juniper Junos Os Evolved.

## How do I fix CVE-2025-21600?

No fix has been published for CVE-2025-21600 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-21600 being exploited?

There is no known exploitation of CVE-2025-21600 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-2025-21600 and fix it if it is affected.

What it is: CVE-2025-21600 is a high-severity denial of service vulnerability in Juniper Junos, published on 9 Jan 2025. 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-2025-21600 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-2025-21600/ (Markdown: https://insights.sbomify.com/CVE-2025-21600/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21600
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21600
- OSV: https://osv.dev/vulnerability/CVE-2025-21600

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-21600/
Summaries are generated and may contain mistakes; the official description above is the record.