# CVE-2024-39536: Junos OS and Junos OS Evolved: Flaps of BFD sessions with authentication cause a ppmd memory leak

> An unauthenticated adjacent attacker can cause a memory leak and denial of service by flapping authenticated BFD sessions in Junos OS.

- **Severity:** Medium 6.0 (`CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **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 Jul 2024
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-vpjj-mfgj-j3mj

## What is CVE-2024-39536?

CVE-2024-39536 is a medium-severity denial of service vulnerability in Juniper Junos, published on 11 Jul 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A Missing Release of Memory after Effective Lifetime vulnerability in the Periodic Packet Management Daemon (ppmd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a 

Denial-of-Service (DoS).

When a BFD session configured with authentication flaps, ppmd memory can leak. Whether the leak happens depends on a race condition which is outside the attackers control. This issue only affects BFD operating in distributed aka delegated (which is the default behavior) or inline mode.

Whether the leak occurs can be monitored with the following CLI command:

> show ppm request-queue

FPC     Pending-request
fpc0                   2
request-total-pending: 2

where a continuously increasing number of pending requests is indicative of the leak. 

This issue affects:

Junos OS:

  *  All versions before 21.2R3-S8,
  *  21.4 versions before 21.4R3-S7,
  *  22.1 versions before 22.1R3-S4,
  *  22.2 versions before 22.2R3-S4, 
  *  22.3 versions before 22.3R3,
  *  22.4 versions before 22.4R2-S2, 22.4R3.

Junos OS Evolved:
  *  All versions before 21.2R3-S8-EVO,
  *  21.4-EVO versions before 21.4R3-S7-EVO,
  *  22.2-EVO versions before 22.2R3-S4-EVO,
  *  22.3-EVO versions before 22.3R3-EVO,
  *  22.4-EVO versions before 22.4R3-EVO.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2024-39536?

It affects 2 products.


Products: Juniper Junos, Juniper Junos Os Evolved.

## How do I fix CVE-2024-39536?

No fix has been published for CVE-2024-39536 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-39536 being exploited?

There is no known exploitation of CVE-2024-39536 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-2024-39536 and fix it if it is affected.

What it is: CVE-2024-39536 is a medium-severity denial of service vulnerability in Juniper Junos, published on 11 Jul 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-2024-39536 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-2024-39536/ (Markdown: https://insights.sbomify.com/CVE-2024-39536/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-39536
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-39536
- OSV: https://osv.dev/vulnerability/CVE-2024-39536

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-39536/
Summaries are generated and may contain mistakes; the official description above is the record.