# What is CVE-2021-1384?

> CVE-2021-1384 is a high-severity flaw (CVSS 7.2) in IOS XE from Cisco, published on 24 March 2021. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 35%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2021-1384

## At a glance

- **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.
- **Precursor Intelligence risk score:** 53 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.2 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 35% (latest exploit-likelihood forecast)
- **Published:** 24 March 2021
- **Record last updated:** 7 November 2023
- **Main product:** IOS XE from Cisco
- **Affected products:** 1

## What is CVE-2021-1384? In plain terms

It can be attacked from anywhere on the internet with an administrator account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The official description

A vulnerability in Cisco IOx application hosting environment of Cisco IOS XE Software could allow an authenticated, remote attacker to inject commands into the underlying operating system as the root user. This vulnerability is due to incomplete validation of fields in the application packages loaded onto IOx. An attacker could exploit this vulnerability by creating a crafted application .tar file and loading it onto the device. A successful exploit could allow the attacker to perform command injection into the underlying operating system as the root user.

### What kind of flaw is it?

- CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
- CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection')

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Easy: no special conditions
- Login needed first: An administrator account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

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

## Is CVE-2021-1384 being exploited? Not that we know of

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 35%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 35%, 35%, 35%, 35%, 35%, 35%, 35%.

### Timeline

- 24 March 2021: Published
- 7 November 2023: Record last updated
- 19 November 2025: Exploit likelihood fell
- 22 November 2025: Exploit likelihood jumped

### How Precursor Intelligence ranks it

CVE-2021-1384 scores **53 out of 100 (Medium)**, with the action "Plan remediation".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2021-1384?

The published record lists 1 product. Versions are as published: "before 16.6.9" means every version up to, but not including, 16.6.9.

- [IOS XE](https://www.precursorintelligence.com/product/cisco/ios_xe) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 16.6.9, 16.9.0 to before 16.9.7, 17.3.2 to before 17.3.3, 17.4.0 to before 17.4.2, 17.5.0

## How do I fix CVE-2021-1384?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

### References

- [tools.cisco.com](https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iox-cmdinj-RkSURGHG) (Vendor advisory)
- [github.com](https://github.com/orangecertcc/security-research/security/advisories/GHSA-h332-fj6p-2232) (Exploit, Third-party advisory)

## Questions

### What is CVE-2021-1384?

CVE-2021-1384 is a high-severity flaw in IOS XE from Cisco, published on 24 March 2021. It can be attacked from anywhere on the internet with an administrator account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2021-1384?

It scores 7.2 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2021-1384 is 53 out of 100, which is Medium. Its action is "Plan remediation". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

### Is CVE-2021-1384 being exploited?

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 35%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2021-1384 affect?

For IOS XE from Cisco: before 16.6.9, 16.9.0 to before 16.9.7, 17.3.2 to before 17.3.3, 17.4.0 to before 17.4.2, 17.5.0.

### How do I fix CVE-2021-1384?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

## Does CVE-2021-1384 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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