# What is CVE-2017-3854?

> CVE-2017-3854 is a high-severity flaw (CVSS 8.8) in Wireless LAN Controller Software from Cisco, published on 15 March 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 1.4%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2017-3854

## 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 8.8 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:** 1.4% (latest exploit-likelihood forecast)
- **Published:** 15 March 2017
- **Record last updated:** 20 April 2025
- **Main product:** Wireless LAN Controller Software from Cisco
- **Affected products:** 12

## What is CVE-2017-3854? In plain terms

An attacker has to be on the same local network without logging in, 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 the mesh code of Cisco Wireless LAN Controller (WLC) software could allow an unauthenticated, remote attacker to impersonate a WLC in a meshed topology. The vulnerability is due to insufficient authentication of the parent access point in a mesh configuration. An attacker could exploit this vulnerability by forcing the target system to disconnect from the correct parent access point and reconnect to a rogue access point owned by the attacker. An exploit could allow the attacker to control the traffic flowing through the impacted access point or take full control of the target system. This vulnerability affects the following products running a vulnerable version of Wireless LAN Controller software and configured for meshed mode: Cisco 8500 Series Wireless Controller, Cisco 5500 Series Wireless Controller, Cisco 2500 Series Wireless Controller, Cisco Flex 7500 Series Wireless Controller, Cisco Virtual Wireless Controller, Wireless Services Module 2 (WiSM2). Note that additional configuration is needed in addition to upgrading to a fixed release. Cisco Bug IDs: CSCuc98992 CSCuu14804.

### What kind of flaw is it?

- CWE-287: Improper Authentication

### How an attack on it works

- Where an attacker can be: On the same local network
- 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 read data, change data and take it offline

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

## Is CVE-2017-3854 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 1.4%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 1.4%, 1.4%, 1.4%, 1.4%, 1.4%, 1.4%, 1.4%.

### Timeline

- 15 March 2017: Published
- 20 April 2025: Record last updated

### How Precursor Intelligence ranks it

CVE-2017-3854 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-2017-3854?

The published record lists 12 products.

- [Wireless LAN Controller Software](https://www.precursorintelligence.com/product/cisco/wireless_lan_controller_software) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): 6.0199.4, 7.41.54, 7.0220.0, 7.0250.0, 16.088.0
- [2500 Wireless LAN Controller](https://www.precursorintelligence.com/product/cisco/2500_wireless_lan_controller) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [2504 Wireless LAN Controller](https://www.precursorintelligence.com/product/cisco/2504_wireless_lan_controller) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [5500 Wireless LAN Controller](https://www.precursorintelligence.com/product/cisco/5500_wireless_lan_controller) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [5508 Wireless LAN Controller](https://www.precursorintelligence.com/product/cisco/5508_wireless_lan_controller) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [7500 Wireless LAN Controller](https://www.precursorintelligence.com/product/cisco/7500_wireless_lan_controller) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [7510 Wireless LAN Controller](https://www.precursorintelligence.com/product/cisco/7510_wireless_lan_controller) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [8510 Wireless LAN Controller](https://www.precursorintelligence.com/product/cisco/8510_wireless_lan_controller) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [8540 Wireless LAN Controller](https://www.precursorintelligence.com/product/cisco/8540_wireless_lan_controller) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Virtual Wireless Controller](https://www.precursorintelligence.com/product/cisco/virtual_wireless_controller) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified
- [Wireless LAN Controller Firmware](https://www.precursorintelligence.com/product/cisco/wireless_lan_controller_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): 8.0.72.140
- [Wireless Service Module 2](https://www.precursorintelligence.com/product/cisco/wireless_service_module_2) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Hardware): version not specified

## How do I fix CVE-2017-3854?

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-20170315-wlc-mesh) (Vendor advisory)
- [securityfocus.com](http://www.securityfocus.com/bid/96911) (Third-party advisory, Vulnerability database)
- [securitytracker.com](http://www.securitytracker.com/id/1038041) (Third-party advisory, Vulnerability database)

## Questions

### What is CVE-2017-3854?

CVE-2017-3854 is a high-severity flaw in Wireless LAN Controller Software from Cisco, published on 15 March 2017. An attacker has to be on the same local network without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2017-3854?

It scores 8.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2017-3854 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-2017-3854 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 1.4%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2017-3854 affect?

For Wireless LAN Controller Software from Cisco: 6.0199.4, 7.41.54, 7.0220.0, 7.0250.0, 16.088.0. The record lists 12 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2017-3854?

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-2017-3854 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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