CVE-2017-12336 [Medium] | Input Validation Bypass in Nx-Os

A vulnerability in the TCL scripting subsystem of Cisco NX-OS System Software could allow an authenticated, local attacker to escape the interactive TCL shell and gain unauthorized access to the underlying operating system of the device. The vulnerability exists due to insufficient input validation of user-supplied files passed to the interactive TCL shell of the affected device. An attacker could exploit this vulnerability to escape the scripting sandbox and execute arbitrary commands on the underlying operating system with the privileges of the authenticated user. To exploit this vulnerability, an attacker must have local access and be authenticated to the targeted device with administrative or tclsh execution privileges. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Fabric Extenders, 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 standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, Unified Computing System Manager. Cisco Bug IDs: CSCve93750, CSCve93762, CSCve93763, CSCvg04127.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-01-12	0.04%	0.10%	+0.06%
2	2023-03-07	1.36%	0.04%	-1.32%
3	2022-02-04	—	1.36%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-01-12

0.04%

0.10%

+0.06%

2023-03-07

1.36%

0.04%

-1.32%

2022-02-04

—

1.36%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
4.2	3.0	MEDIUM	`CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. 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:H) They need powerful rights—admin, root, or similar—before this pays off. 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:L) Some sensitive info could get out, but not a total data dump. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	0.8	3.4	[email protected]
4.6	2.0	MEDIUM	`AV:L/AC:L/Au:N/C:P/I:P/A:P` Click to expand Access vector (AV:L) Requires local access to the target system. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	3.9	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

4.2

3.0

MEDIUM

CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L Click to expand

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:H): They need powerful rights—admin, root, or similar—before this pays off.
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:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

0.8

3.4

[email protected]

4.6

2.0

MEDIUM

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

Access vector (AV:L): Requires local access to the target system.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

3.9

6.4

[email protected]

Affected software / configurations for CVE-2017-12336

Vendor	Product	Version	Raw CPE
cisco	nx-os	6.0\(2\)a8\(3\)	cpe:2.3:o:cisco:nx-os:6.0\(2\)a8\(3\):::::::*
cisco	nx-os	8.0\(1\)	cpe:2.3:o:cisco:nx-os:8.0\(1\):::::::*
cisco	nx-os	8.1\(0\)bd\(0.20\)	cpe:2.3:o:cisco:nx-os:8.1\(0\)bd\(0.20\):::::::*
cisco	nx-os	8.1\(0.2\)s0	cpe:2.3:o:cisco:nx-os:8.1\(0.2\)s0:::::::*
cisco	nx-os	8.1\(0.59\)s0	cpe:2.3:o:cisco:nx-os:8.1\(0.59\)s0:::::::*
cisco	nx-os	8.1\(1\)s5	cpe:2.3:o:cisco:nx-os:8.1\(1\)s5:::::::*
cisco	unified_computing_system	7.0\(0\)hsk\(0.357\)	cpe:2.3:a:cisco:unified_computing_system:7.0\(0\)hsk\(0.357\):::::::*

References for CVE-2017-12336

URL	Tags
http://www.securityfocus.com/bid/102168
http://www.securitytracker.com/id/1039936	Third Party Advisory VDB Entry
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20171129-nxos5	Vendor Advisory

URL

CVE-2017-12336

Exploit prediction scoring system (EPSS) score for CVE-2017-12336

Common vulnerability scoring system (CVSS) metrics for CVE-2017-12336

Weakness enumeration for CVE-2017-12336

Affected software / configurations for CVE-2017-12336

References for CVE-2017-12336