CVE-2021-0255

Root file writes via SUID ethtraceroute execution

Published Apr 22, 2021 · Updated Sep 16, 2024

Local privilege escalation in Juniper Networks Junos OS allows local users with shell access to write files as root through ethtraceroute. The operating-system image installs ethtraceroute as a root-owned SUID executable, so an ordinary shell user's invocation executes with root identity. Exploitation requires an authenticated local shell session; the published mechanism establishes root-level filesystem writes but does not disclose the crafted input.

CVSS severity5.5
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Local privilege escalation in Juniper Networks Junos OS allows local users with shell access to write files as root through ethtraceroute. The operating-system image installs ethtraceroute as a root-owned SUID executable, so an ordinary shell user's invocation executes with root identity. Exploitation requires an authenticated local shell session; the published mechanism establishes root-level filesystem writes but does not disclose the crafted input.

The record

CVE
CVE-2021-0255
Published
Apr 22, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-250, CWE-269, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=15.1X49 <15.1X49-D240
  2. Affected versionversion=17.3 <17.3R3-S11
  3. Affected versionversion=17.4 <17.4R3-S4
  4. Affected versionversion=18.1 <18.1R3-S12
  5. Affected versionversion=18.2 <18.2R3-S7
  6. Affected versionversion=18.3 <18.3R3-S4
  7. Affected versionversion=18.4 <18.4R2-S7
  8. Affected versionversion=19.1 <19.1R1-S6, 19.1R2-S2, 19.1R3-S4
  9. Affected versionversion=19.3 <19.3R3-S2
  10. Affected versionversion=19.4 <19.4R3-S1
  11. Affected versionversion=20.1 <20.1R2, 20.1R3
  12. Affected versionversion=20.2 <20.2R2-S1, 20.2R3
  13. Affected versionversion=20.3 <20.3R1-S1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Juniper Networks · Junos OSversion=15.1X49 <15.1X49-D240; version=17.3 <17.3R3-S11; version=17.4 <17.4R3-S4; version=18.1 <18.1R3-S12; version=18.2 <18.2R3-S7; version=18.3 <18.3R3-S4; version=18.4 <18.4R2-S7; version=19.1 <19.1R1-S6, 19.1R2-S2, 19.1R3-S4; version=19.3 <19.3R3-S2; version=19.4 <19.4R3-S1; version=20.1 <20.1R2, 20.1R3; version=20.2 <20.2R2-S1, 20.2R3; version=20.3 <20.3R1-S1

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C
5.5Juniper NetworksCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-250Execution with Unnecessary Privileges
CWE-269Improper Privilege Management
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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