CVE-2021-40120

6.5 MEDIUM 2% exploit odds Fix listed

What it is

A vulnerability in the web-based management interface of certain Cisco Small Business RV Series Routers could allow an authenticated, remote attacker with administrative privileges to inject arbitrary commands into the underlying operating system and execute them using root-level privileges. This vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending malicious input to a specific field in the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying Linux operating system as a user with root-level privileges.

At a glance

Exploitability: Can be exploited over the network with an admin-level account. High risk of data exposure, data tampering.
Exploit odds: 2.0% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2021-11-04 16:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 04:06 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 2.0% in the next 30 days (EPSS).
Severity: 6.5 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2021-11-04 16:15 UTC
Last modified: 2026-06-17 04:06 UTC
Exploit probability: 2.0% · EPSS, next 30 days
Weakness: CWE-20 · Improper input validation
Record status: Modified

Affected

Cisco iOS Xr 4.2.3.06
Cisco Application Extension Platform 1.5.1.13

Attack profile CVSS 3.1 · 6.5

Attack vector: Network
Complexity: Low
Privileges needed: High
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-40120.md and follow it. Check whether this project is affected by CVE-2021-40120. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

· More options · Status badge

Download Square Reddit

Fix and advisories

References

NVD record · CVE.org record