# CVE-2024-39526: Denial of service in Junos OS

> Attackers can cause a denial of service by sending malformed DHCP packets to Juniper devices with DHCP snooping 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/R:U`)
- **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:** 11 Oct 2024
- **Updated:** 11 Oct 2024
- **Also known as:** GHSA-qxf5-vpwf-vj9q

## What is CVE-2024-39526?

CVE-2024-39526 is a high-severity denial of service vulnerability in Juniper Junos, published on 11 Oct 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An Improper Handling of Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS on MX Series with MPC10/MPC11/LC9600 line cards, EX9200 with EX9200-15C lines cards, MX304 devices, and Juniper Networks Junos OS Evolved on PTX Series, allows an attacker sending malformed DHCP packets to cause ingress packet processing to stop, leading to a Denial of Service (DoS).  Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition.

This issue only occurs if DHCP snooping is enabled. See configuration below.

This issue can be detected using following commands. Their output will display the interface status going down:

user@device>show interfaces <if--x/x/x>
user@device>show log messages | match <if--x/x/x>
user@device>show log messages ==> will display the "[Error] Wedge-Detect : Host Loopback Wedge Detected: PFE: no," logs.

This issue affects:
Junos OS on 

MX Series 

with MPC10/MPC11/LC9600 line cards, EX9200 with EX9200-15C line cards, and MX304: 

  *  All versions before 21.2R3-S7, 
  *  from 21.4 before 21.4R3-S6, 
  *  from 22.2 before 22.2R3-S3, 
  *  all versions of 22.3,
  *  from 22.4 before 22.4R3, 
  *  from 23.2 before 23.2R2; 

Junos OS Evolved on PTX Series: 
  *  from 19.3R1-EVO before 21.2R3-S8-EVO,

  *  from 21.4-EVO before 21.4R3-S7-EVO, 
  *  from 22.1-EVO before 22.1R3-S6-EVO, 
  *  from 22.2-EVO before 22.2R3-S5-EVO, 
  *  from 22.3-EVO before 22.3R3-S3-EVO, 
  *  from 22.4-EVO before 22.4R3-S1-EVO, 
  *  from 23.2-EVO before 23.2R2-S2-EVO, 
  *  from 23.4-EVO before 23.4R2-EVO.

Junos OS Evolved releases prior to 19.3R1-EVO are unaffected by this vulnerability

Weakness: CWE-755 (Improper Handling of Exceptional Conditions)

## Which versions are affected by CVE-2024-39526?

It affects 2 products.


Products: Juniper Junos, Juniper Junos Os Evolved.

## How do I fix CVE-2024-39526?

No fix has been published for CVE-2024-39526 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-39526 being exploited?

There is no known exploitation of CVE-2024-39526 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-2024-39526 and fix it if it is affected.

What it is: CVE-2024-39526 is a high-severity denial of service vulnerability in Juniper Junos, published on 11 Oct 2024. 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-2024-39526 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-2024-39526/ (Markdown: https://insights.sbomify.com/CVE-2024-39526/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-39526
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-39526
- OSV: https://osv.dev/vulnerability/CVE-2024-39526

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-39526/
Summaries are generated and may contain mistakes; the official description above is the record.