CVE-2017-3854 [High] | Authentication Bypass in Wireless Lan Controller F…

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.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	1.00%	1.39%	+0.39%
2	2026-04-30	1.36%	1.00%	-0.35%
3	2025-03-30	—	1.36%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

1.00%

1.39%

+0.39%

2026-04-30

1.36%

1.00%

-0.35%

2025-03-30

—

1.36%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.8	3.1	HIGH	`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:A) Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.8	5.9	[email protected]
8.3	2.0	HIGH	`AV:A/AC:L/Au:N/C:C/I:C/A:C` Click to expand Access vector (AV:A) Requires access to an adjacent network segment. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:C) Complete confidentiality impact. Integrity impact (I:C) Complete integrity impact. Availability impact (A:C) Complete availability impact.	6.5	10.0	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.8

3.1

HIGH

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

Attack vector (AV:A): Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

2.8

5.9

[email protected]

8.3

2.0

HIGH

AV:A/AC:L/Au:N/C:C/I:C/A:C Click to expand

Access vector (AV:A): Requires access to an adjacent network segment.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:C): Complete confidentiality impact.
Integrity impact (I:C): Complete integrity impact.
Availability impact (A:C): Complete availability impact.

6.5

10.0

[email protected]

Affected software / configurations for CVE-2017-3854

Vendor	Product	Version	Raw CPE
cisco	wireless_lan_controller_firmware	8.0.72.140	cpe:2.3:o:cisco:wireless_lan_controller_firmware:8.0.72.140:::::::*
cisco	wireless_lan_controller_software	6.0199.4	cpe:2.3:o:cisco:wireless_lan_controller_software:6.0199.4:::::::*
cisco	wireless_lan_controller_software	7.41.54	cpe:2.3:o:cisco:wireless_lan_controller_software:7.41.54:::::::*
cisco	wireless_lan_controller_software	7.0220.0	cpe:2.3:o:cisco:wireless_lan_controller_software:7.0220.0:::::::*
cisco	wireless_lan_controller_software	7.0250.0	cpe:2.3:o:cisco:wireless_lan_controller_software:7.0250.0:::::::*
cisco	wireless_lan_controller_software	16.088.0	cpe:2.3:o:cisco:wireless_lan_controller_software:16.088.0:::::::*

References for CVE-2017-3854

URL	Tags
http://www.securityfocus.com/bid/96911	Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1038041	Third Party Advisory VDB Entry
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170315-wlc-mesh	Vendor Advisory

URL

CVE-2017-3854

Exploit prediction scoring system (EPSS) score for CVE-2017-3854

Common vulnerability scoring system (CVSS) metrics for CVE-2017-3854

Weakness enumeration for CVE-2017-3854

Affected software / configurations for CVE-2017-3854

References for CVE-2017-3854