# CVE-2024-39555: Junos OS and Junos OS Evolved: Receipt of a specific malformed BGP update causes the session to reset

> Remote attackers can cause a sustained denial of service by sending malformed BGP updates to Juniper devices with segment routing enabled.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/R:A`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Jul 2024
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-93cc-g9p8-jrr7

## What is CVE-2024-39555?

CVE-2024-39555 is a high-severity denial of service vulnerability in Juniper Junos, published on 10 Jul 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An Improper Handling of Exceptional Conditions vulnerability in the Routing Protocol Daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows an attacker sending a specific malformed BGP update message to cause the session to reset, resulting in a Denial of Service (DoS).  Continued receipt and processing of these malformed BGP update messages will create a sustained Denial of Service (DoS) condition.

Upon receipt of a BGP update message over an established BGP session containing a specifically malformed tunnel encapsulation attribute, when segment routing is enabled, internal processing of the malformed attributes within the update results in improper parsing of remaining attributes, leading to session reset:

BGP SEND Notification code 3 (Update Message Error) subcode 1 (invalid attribute list)

Only systems with segment routing enabled are vulnerable to this issue.

This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations, and requires a remote attacker to have at least one established BGP session.

This issue affects:

Junos OS: 

  *  All versions before 21.4R3-S8, 
  *  from 22.2 before 22.2R3-S4, 
  *  from 22.3 before 22.3R3-S3, 
  *  from 22.4 before 22.4R3-S3, 
  *  from 23.2 before 23.2R2-S1, 
  *  from 23.4 before 23.4R1-S2, 23.4R2.

Junos OS Evolved: 

  *  All versions before 21.4R3-S8-EVO, 
  *  from 22.2-EVO before 22.2R3-S4-EVO, 
  *  from 22.3-EVO before 22.3R3-S3-EVO, 
  *  from 22.4-EVO before 22.4R3-S3-EVO, 
  *  from 23.2-EVO before 23.2R2-S1-EVO, 
  *  from 23.4-EVO before 23.4R1-S2-EVO, 23.4R2-EVO.

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

## Which versions are affected by CVE-2024-39555?

It affects 2 products.


Products: Juniper Junos, Juniper Junos Os Evolved.

## How do I fix CVE-2024-39555?

No fix has been published for CVE-2024-39555 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-39555 being exploited?

There is no known exploitation of CVE-2024-39555 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-2024-39555 and fix it if it is affected.

What it is: CVE-2024-39555 is a high-severity denial of service vulnerability in Juniper Junos, published on 10 Jul 2024. 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-2024-39555 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-2024-39555/ (Markdown: https://insights.sbomify.com/CVE-2024-39555/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-39555
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-39555
- OSV: https://osv.dev/vulnerability/CVE-2024-39555

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-39555/
Summaries are generated and may contain mistakes; the official description above is the record.