# What is CVE-2017-3883?

> CVE-2017-3883 is a high-severity flaw (CVSS 8.6) in Firepower Extensible Operating System from Cisco, published on 19 October 2017. 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 4.5%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2017-3883

## 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 8.6 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:** 4.5% (latest exploit-likelihood forecast)
- **Published:** 19 October 2017
- **Record last updated:** 20 April 2025
- **Main product:** Firepower Extensible Operating System from Cisco
- **Affected products:** 47

## What is CVE-2017-3883? In plain terms

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

### The official description

A vulnerability in the authentication, authorization, and accounting (AAA) implementation of Cisco Firepower Extensible Operating System (FXOS) and NX-OS System Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability occurs because AAA processes prevent the NX-OS System Manager from receiving keepalive messages when an affected device receives a high rate of login attempts, such as in a brute-force login attack. System memory can run low on the FXOS devices under the same conditions, which could cause the AAA process to unexpectedly restart or cause the device to reload. An attacker could exploit this vulnerability by performing a brute-force login attack against a device that is configured with AAA security services. A successful exploit could allow the attacker to cause the affected device to reload. This vulnerability affects the following Cisco products if they are running Cisco FXOS or NX-OS System Software that is configured for AAA services: Firepower 4100 Series Next-Generation Firewall, Firepower 9300 Security Appliance, Multilayer Director Switches, Nexus 1000V Series Switches, Nexus 1100 Series Cloud Services Platforms, Nexus 2000 Series Switches, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 5000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, Unified Computing System (UCS) 6100 Series Fabric Interconnects, UCS 6200 Series Fabric Interconnects, UCS 6300 Series Fabric Interconnects. Cisco Bug IDs: CSCuq58760, CSCuq71257, CSCur97432, CSCus05214, CSCux54898, CSCvc33141, CSCvd36971, CSCve03660.

### What kind of flaw is it?

- CWE-770: Allocation of Resources Without Limits or Throttling

### 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: No login needed
- 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:N/UI:N/S:C/C:N/I:N/A:H`

## Is CVE-2017-3883 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 4.5%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 4.5%, 4.5%, 4.5%, 4.5%, 4.5%, 4.5%, 4.5%.

### Timeline

- 19 October 2017: Published
- 20 April 2025: Record last updated

### How Precursor Intelligence ranks it

CVE-2017-3883 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-2017-3883?

The published record lists 47 products.

- [Firepower Extensible Operating System](https://www.precursorintelligence.com/product/cisco/firepower_extensible_operating_system) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): up to 2.3
- [NX-OS](https://www.precursorintelligence.com/product/cisco/nx-os) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): up to 4.1, up to 6.0, up to 5.2, up to 2.2, 6.1, 6.2, 6.3, 7.0(3)i3(1), 7.1(0.1), 7.0, 7.3, 8.1, 8.2
- [9500 R](https://www.precursorintelligence.com/product/cisco/9500_r) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Firepower 4100](https://www.precursorintelligence.com/product/cisco/firepower_4100) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Firepower 9300](https://www.precursorintelligence.com/product/cisco/firepower_9300) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Fxos](https://www.precursorintelligence.com/product/cisco/fxos) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): 2.3
- [Mds 9000](https://www.precursorintelligence.com/product/cisco/mds_9000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 1000v](https://www.precursorintelligence.com/product/cisco/nexus_1000v) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 1100v](https://www.precursorintelligence.com/product/cisco/nexus_1100v) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 2000](https://www.precursorintelligence.com/product/cisco/nexus_2000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3000](https://www.precursorintelligence.com/product/cisco/nexus_3000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3016](https://www.precursorintelligence.com/product/cisco/nexus_3016) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3016q](https://www.precursorintelligence.com/product/cisco/nexus_3016q) 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 3064t](https://www.precursorintelligence.com/product/cisco/nexus_3064t) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3064x](https://www.precursorintelligence.com/product/cisco/nexus_3064x) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3500](https://www.precursorintelligence.com/product/cisco/nexus_3500) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3524](https://www.precursorintelligence.com/product/cisco/nexus_3524) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 3548](https://www.precursorintelligence.com/product/cisco/nexus_3548) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5000](https://www.precursorintelligence.com/product/cisco/nexus_5000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5010](https://www.precursorintelligence.com/product/cisco/nexus_5010) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5010p Switch](https://www.precursorintelligence.com/product/cisco/nexus_5010p_switch) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5500](https://www.precursorintelligence.com/product/cisco/nexus_5500) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5548p](https://www.precursorintelligence.com/product/cisco/nexus_5548p) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5548up](https://www.precursorintelligence.com/product/cisco/nexus_5548up) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5596t](https://www.precursorintelligence.com/product/cisco/nexus_5596t) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5596up](https://www.precursorintelligence.com/product/cisco/nexus_5596up) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5600](https://www.precursorintelligence.com/product/cisco/nexus_5600) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 56128p](https://www.precursorintelligence.com/product/cisco/nexus_56128p) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5624q](https://www.precursorintelligence.com/product/cisco/nexus_5624q) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5648q](https://www.precursorintelligence.com/product/cisco/nexus_5648q) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5672up](https://www.precursorintelligence.com/product/cisco/nexus_5672up) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 5696q](https://www.precursorintelligence.com/product/cisco/nexus_5696q) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 6000](https://www.precursorintelligence.com/product/cisco/nexus_6000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 6001](https://www.precursorintelligence.com/product/cisco/nexus_6001) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 6004](https://www.precursorintelligence.com/product/cisco/nexus_6004) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 6004x](https://www.precursorintelligence.com/product/cisco/nexus_6004x) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 7000](https://www.precursorintelligence.com/product/cisco/nexus_7000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 7000 10-Slot](https://www.precursorintelligence.com/product/cisco/nexus_7000_10-slot) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 7000 18-Slot](https://www.precursorintelligence.com/product/cisco/nexus_7000_18-slot) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 7000 9-Slot](https://www.precursorintelligence.com/product/cisco/nexus_7000_9-slot) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 7700](https://www.precursorintelligence.com/product/cisco/nexus_7700) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Nexus 9000](https://www.precursorintelligence.com/product/cisco/nexus_9000) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [UCS 6100](https://www.precursorintelligence.com/product/cisco/ucs_6100) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [UCS 6200](https://www.precursorintelligence.com/product/cisco/ucs_6200) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [UCS 6300](https://www.precursorintelligence.com/product/cisco/ucs_6300) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified

## How do I fix CVE-2017-3883?

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-20171018-aaavty) (Vendor advisory)
- [securityfocus.com](http://www.securityfocus.com/bid/101493) (Third-party advisory, Vulnerability database)
- [securitytracker.com](http://www.securitytracker.com/id/1039614) (Third-party advisory, Vulnerability database)
- [support.hpe.com](https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbst03846en_us)

## Questions

### What is CVE-2017-3883?

CVE-2017-3883 is a high-severity flaw in Firepower Extensible Operating System from Cisco, published on 19 October 2017. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

### How serious is CVE-2017-3883?

It scores 8.6 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2017-3883 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-2017-3883 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 4.5%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2017-3883 affect?

For Firepower Extensible Operating System from Cisco: up to 2.3. The record lists 47 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2017-3883?

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-2017-3883 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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