# What is CVE-2018-0309?

> CVE-2018-0309 is a high-severity flaw (CVSS 7.7) in NX-OS from Cisco, published on 21 June 2018. 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 2.0%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2018-0309

## At a glance

- **Verdict:** Plan it in. No sign of exploitation and a low forecast. Patch it in your normal update cycle.
- **Precursor Intelligence risk score:** 47 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.7 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:** 2.0% (latest exploit-likelihood forecast)
- **Published:** 21 June 2018
- **Record last updated:** 9 October 2019
- **Main product:** NX-OS from Cisco
- **Affected products:** 40

## What is CVE-2018-0309? In plain terms

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

### The official description

A vulnerability in the implementation of a specific CLI command and the associated Simple Network Management Protocol (SNMP) MIB for Cisco NX-OS (in standalone NX-OS mode) on Cisco Nexus 3000 and 9000 Series Switches could allow an authenticated, remote attacker to exhaust system memory on an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to the incorrect implementation of the CLI command, resulting in a failure to free all allocated memory upon completion. An attacker could exploit this vulnerability by authenticating to the affected device and repeatedly issuing a specific CLI command or sending a specific SNMP poll request for a specific Object Identifier (OID). A successful exploit could allow the attacker to cause the IP routing process to restart or to cause a device reset, resulting in a DoS condition. Cisco Bug IDs: CSCvf23136.

### What kind of flaw is it?

- CWE-400: Uncontrolled Resource Consumption

### 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 ordinary user account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can take it offline

Severity vector: `CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H`

## Is CVE-2018-0309 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 2.0%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 2.0%, 2.0%, 2.0%, 2.0%, 2.0%, 2.0%, 2.0%.

### Timeline

- 21 June 2018: Published
- 9 October 2019: Record last updated

### How Precursor Intelligence ranks it

CVE-2018-0309 scores **47 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-2018-0309?

The published record lists 40 products.

- [NX-OS](https://www.precursorintelligence.com/product/cisco/nx-os) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): 7.0(3)i5(2), 7.0(3)i6(1)
- [Nexus 3016](https://www.precursorintelligence.com/product/cisco/nexus_3016) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3048](https://www.precursorintelligence.com/product/cisco/nexus_3048) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3064](https://www.precursorintelligence.com/product/cisco/nexus_3064) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3064-T](https://www.precursorintelligence.com/product/cisco/nexus_3064-t) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 31108pc-V](https://www.precursorintelligence.com/product/cisco/nexus_31108pc-v) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 31108tc-V](https://www.precursorintelligence.com/product/cisco/nexus_31108tc-v) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 31128pq](https://www.precursorintelligence.com/product/cisco/nexus_31128pq) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3132q](https://www.precursorintelligence.com/product/cisco/nexus_3132q) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3132q-V](https://www.precursorintelligence.com/product/cisco/nexus_3132q-v) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3132q-Xl](https://www.precursorintelligence.com/product/cisco/nexus_3132q-xl) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3164q](https://www.precursorintelligence.com/product/cisco/nexus_3164q) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3172](https://www.precursorintelligence.com/product/cisco/nexus_3172) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3172pq-Xl](https://www.precursorintelligence.com/product/cisco/nexus_3172pq-xl) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3172tq](https://www.precursorintelligence.com/product/cisco/nexus_3172tq) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3172tq-32t](https://www.precursorintelligence.com/product/cisco/nexus_3172tq-32t) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3172tq-Xl](https://www.precursorintelligence.com/product/cisco/nexus_3172tq-xl) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3232c](https://www.precursorintelligence.com/product/cisco/nexus_3232c) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3264q](https://www.precursorintelligence.com/product/cisco/nexus_3264q) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9000v](https://www.precursorintelligence.com/product/cisco/nexus_9000v) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 92160yc-X](https://www.precursorintelligence.com/product/cisco/nexus_92160yc-x) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 92300yc](https://www.precursorintelligence.com/product/cisco/nexus_92300yc) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 92304qc](https://www.precursorintelligence.com/product/cisco/nexus_92304qc) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9236c](https://www.precursorintelligence.com/product/cisco/nexus_9236c) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9272q](https://www.precursorintelligence.com/product/cisco/nexus_9272q) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 93108tc-EX](https://www.precursorintelligence.com/product/cisco/nexus_93108tc-ex) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 93120tx](https://www.precursorintelligence.com/product/cisco/nexus_93120tx) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 93128tx](https://www.precursorintelligence.com/product/cisco/nexus_93128tx) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 93180lc-EX](https://www.precursorintelligence.com/product/cisco/nexus_93180lc-ex) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 93180yc-EX](https://www.precursorintelligence.com/product/cisco/nexus_93180yc-ex) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9332pq](https://www.precursorintelligence.com/product/cisco/nexus_9332pq) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9372px](https://www.precursorintelligence.com/product/cisco/nexus_9372px) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9372px-E](https://www.precursorintelligence.com/product/cisco/nexus_9372px-e) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9372tx](https://www.precursorintelligence.com/product/cisco/nexus_9372tx) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9372tx-E](https://www.precursorintelligence.com/product/cisco/nexus_9372tx-e) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9396px](https://www.precursorintelligence.com/product/cisco/nexus_9396px) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9396tx](https://www.precursorintelligence.com/product/cisco/nexus_9396tx) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9504](https://www.precursorintelligence.com/product/cisco/nexus_9504) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9508](https://www.precursorintelligence.com/product/cisco/nexus_9508) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9516](https://www.precursorintelligence.com/product/cisco/nexus_9516) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified

## How do I fix CVE-2018-0309?

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-20180620-n3k-n9k-clisnmp) (Vendor advisory)
- [securitytracker.com](http://www.securitytracker.com/id/1041169) (Third-party advisory, Vulnerability database)

## Questions

### What is CVE-2018-0309?

CVE-2018-0309 is a high-severity flaw in NX-OS from Cisco, published on 21 June 2018. It can be attacked from anywhere on the internet with an ordinary user account, and nobody has to click anything. If it works, the attacker can take it offline.

### How serious is CVE-2018-0309?

It scores 7.7 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2018-0309 is 47 out of 100, which is Medium. Its action is "Plan remediation". No sign of exploitation and a low forecast. Patch it in your normal update cycle.

### Is CVE-2018-0309 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 2.0%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2018-0309 affect?

For NX-OS from Cisco: 7.0(3)i5(2), 7.0(3)i6(1). The record lists 40 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2018-0309?

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-2018-0309 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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