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Cisco Security Advisory

Cisco NX-OS Software Python Parser Privilege Escalation Vulnerability

Medium
Advisory ID:
cisco-sa-20190515-nxos-pyth-escal
First Published:
2019 May 15 16:00 GMT
Last Updated:
2021 August 25 15:49 GMT
Version 1.2:
Final
Workarounds:
No workarounds available
CVE-2019-1727
CWE-264
CVSS Score:
Base 4.2Click Icon to Copy Verbose Score
CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L/E:X/RL:X/RC:X
CVE-2019-1727
CWE-264

Summary

  • Update from August 25, 2021: Cisco found that this vulnerability was present in additional releases of Cisco NX-OS Software with the introduction of Python 3 support. For more information, see the Fixed Software section of this advisory.

    A vulnerability in the Python scripting subsystem of Cisco NX-OS Software could allow an authenticated, local attacker to escape the Python parser and issue arbitrary commands to elevate the attacker's privilege level.

    This vulnerability is due to insufficient sanitization of user-supplied parameters that are passed to certain Python functions in the scripting sandbox of the affected device. An attacker could exploit this vulnerability to escape the scripting sandbox and execute arbitrary commands to elevate the attacker's privilege level.

    To exploit this vulnerability, the attacker must have local access and be authenticated to the targeted device with administrative or Python execution privileges. These requirements could limit the possibility of a successful exploit.

    Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

    This advisory is available at the following link:
    https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190515-nxos-pyth-escal

Affected Products

  • Vulnerable Products

    This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco NX-OS Software:

    • MDS 9000 Series Multilayer Switches
    • Nexus 3000 Series Switches
    • Nexus 3500 Platform Switches
    • Nexus 3600 Platform 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 Switching Platform

    For information about which Cisco NX-OS Software releases are vulnerable, see the Fixed Software section of this advisory.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.

    Cisco has confirmed that this vulnerability does not affect the following Cisco products:

    • Firepower 2100 Series
    • Firepower 4100 Series
    • Firepower 9300 Security Appliances
    • Nexus 1000V Switch for Microsoft Hyper-V
    • Nexus 1000V Switch for VMware vSphere
    • Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode
    • UCS 6200 Series Fabric Interconnects
    • UCS 6300 Series Fabric Interconnects
    • UCS 6400 Series Fabric Interconnects

Workarounds

  • There are no workarounds that address this vulnerability. However, an administrator can reduce exposure to this vulnerability by ensuring that only highly trusted users are allowed to access the Python sandbox.

Fixed Software

  • Cisco has released free software updates that address the vulnerabilities described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license: https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

    Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades.

    When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page, to determine exposure and a complete upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.

    Customers Without Service Contracts

    Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html

    Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.

    Fixed Releases

    At the time of publication, the release information in the following table(s) was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

    The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerability described in this advisory and which release included the fix for this vulnerability.

    MDS 9000 Series Multilayer Switches: CSCvi99284 and CSCvy26265

    Cisco NX-OS Software Release First Fixed Release for This Vulnerability
    5.2 8.1(1b)
    6.2 8.1(1b)
    7.3 8.1(1b)
    8.1 8.1(1b)
    8.2 8.3(1)
    8.3 8.3(1)
    8.4 8.4(2d)1 (Future release)

    1. 8.4(2) is the first vulnerable release due to the introduction of Python 3.

    Nexus 3000 Series Switches, Nexus 3500 Platform Switches, and Nexus 9000 Series Switches in Standalone NX-OS Mode: CSCvh24788 and CSCvy08606

    Cisco NX-OS Software Release First Fixed Release for This Vulnerability
    Prior to 7.0(3)I4 7.0(3)I4(8)
    7.0(3)I4 7.0(3)I4(8)
    7.0(3)I5 7.0(3)I7(3)
    7.0(3)I6 7.0(3)I7(3)
    7.0(3)I7 7.0(3)I7(3)
    9.2 Not vulnerable
    9.3 9.3(8)1
    10.1 10.1(2)

    1. 9.3(5) is the first vulnerable release due to the introduction of Python 3.

    Nexus 3600 Platform Switches and Nexus 9500 R-Series Switching Platform: CSCvi99282 and CSCvy08606

    Cisco NX-OS Software Release First Fixed Release for This Vulnerability
    7.0(3) 7.0(3)F3(5)
    9.2 Not vulnerable
    9.3 9.3(8)1
    10.1 10.1(2)

    1. 9.3(5) is the first vulnerable release due to the introduction of Python 3.

    Nexus 5500, 5600, and 6000 Series Switches:CSCvi99288

    Cisco NX-OS Software Release First Fixed Release for This Vulnerability
    Prior to 7.3 7.3(4)N1(1)
    7.3 7.3(4)N1(1)

    Nexus 7000 and 7700 Series Switches: CSCvi99284 and CSCvy26265

    Cisco NX-OS Software Release First Fixed Release for This Vulnerability
    Prior to 6.2 Not vulnerable
    6.2 Not vulnerable
    7.2 7.3(3)D1(1)
    7.3 7.3(3)D1(1)
    8.0 8.3(1)
    8.1 8.3(1)
    8.2 8.3(1)
    8.3 8.3(1)
    8.4 8.4(5)1

    1. 8.4(2) is the first vulnerable release due to the introduction of Python 3.

    Additional Resources

    For help determining the best Cisco NX-OS Software release for a Cisco Nexus Switch, administrators can refer to the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.

    Cisco MDS Series Switches
    Cisco Nexus 1000V for VMware Switch
    Cisco Nexus 3000 Series and 3500 Series Switches
    Cisco Nexus 5000 Series Switches
    Cisco Nexus 5500 Platform Switches
    Cisco Nexus 6000 Series Switches
    Cisco Nexus 7000 Series Switches
    Cisco Nexus 9000 Series Switches
    Cisco Nexus 9000 Series ACI-Mode Switches

    For help determining the best Cisco NX-OS Software release for Cisco UCS, refer to the Recommended Releases documents in the release notes for the device.

Exploitation and Public Announcements

  • The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Source

  • This vulnerability was found during internal security testing.

Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

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Revision History

  • Version Description Section Status Date
    1.2 Added two bug IDs. Updated the first fixed release information for MDS 9000 and Nexus 3000, 7000, and 9000 Series Switches. Header and Fixed Software Final 2021-AUG-25
    1.1 Updated the Nexus 7000 and 7700 Fixed Release table. Fixed Software Final 2019-MAY-28
    1.0 Initial public release. - Final 2019-MAY-15
    Show Less

Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

Subscribe to Cisco Security Notifications

Related to This Advisory