CVE-2020-3403: A vulnerability in the CLI of Cisco IOS XE Software could allow an authenticated, local attacker to inject a command to the underlying operating syste...

Description

A vulnerability in the CLI of Cisco IOS XE Software could allow an authenticated, local attacker to inject a command to the underlying operating system that will execute with root privileges upon the next reboot of the device. The authenticated user must have privileged EXEC permissions on the device. The vulnerability is due to insufficient protection of values passed to a script that executes during device startup. An attacker could exploit this vulnerability by writing values to a specific file. A successful exploit could allow the attacker to execute commands with root privileges each time the affected device is restarted.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.38%

29.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Cisco	Ios Xe	17.2.1

References

Timeline

Published: Sep 24, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-3403?

A vulnerability in the CLI of Cisco IOS XE Software could allow an authenticated, local attacker to inject a command to the underlying operating system that will execute with root privileges upon the next reboot of the device. The authenticated user must have privileged EXEC permissions on the device. The vulnerability is due to insufficient protection of values passed to a script that executes during device startup. An attacker could exploit this vulnerability by writing values to a specific file. A successful exploit could allow the attacker to execute commands with root privileges each time the affected device is restarted.

How severe is CVE-2020-3403?

CVE-2020-3403 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.38% probability of exploitation in the next 30 days.

How do I fix CVE-2020-3403?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.