# CVE-2025-21593: Denial of service in Junos OS

> An unauthenticated attacker can crash the routing daemon on Juniper devices with SRv6 enabled by sending malformed BGP updates, causing a denial of service.

- **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:N/R:A`)
- **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:** 9 Jan 2025
- **Also known as:** GHSA-3wvw-m4vx-cj7h

## What is CVE-2025-21593?

CVE-2025-21593 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 Improper Control of a Resource Through its Lifetime 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).

On devices with SRv6 (Segment Routing over IPv6) enabled, an attacker can send a malformed BGP UPDATE packet which will cause the rpd to crash and restart. Continued receipt of these UPDATE packets will cause a sustained DoS condition. 

This issue affects iBGP and eBGP, and both IPv4 and IPv6 are affected by this vulnerability.This issue affects Junos OS: 

  *  All versions before 21.2R3-S9, 
  *  from 21.4 before 21.4R3-S10, 
  *  from 22.2 before 22.2R3-S5, 
  *  from 22.3 before 22.3R3-S4, 
  *  from 22.4 before 22.4R3-S3, 
  *  from 23.2 before 23.2R2-S2, 
  *  from 23.4 before 23.4R2;

and Junos OS Evolved: 

  *  All versions before 21.2R3-S9-EVO, 
  *  from 21.4-EVO before 21.4R3-S10-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-S3-EVO,
  *  from 23.2-EVO before 23.2R2-S2-EVO, 
  *  from 23.4-EVO before 23.4R2-EVO.

Weakness: CWE-664 (Improper Control of a Resource Through its Lifetime)

## Which versions are affected by CVE-2025-21593?

It affects 2 products.


Products: Juniper Junos, Juniper Junos Os Evolved.

## How do I fix CVE-2025-21593?

No fix has been published for CVE-2025-21593 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-21593 being exploited?

There is no known exploitation of CVE-2025-21593 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-2025-21593 and fix it if it is affected.

What it is: CVE-2025-21593 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-2025-21593 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-2025-21593/ (Markdown: https://insights.sbomify.com/CVE-2025-21593/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21593
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21593
- OSV: https://osv.dev/vulnerability/CVE-2025-21593

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-21593/
Summaries are generated and may contain mistakes; the official description above is the record.