Cisco Security Advisory
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CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
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A vulnerability in the Simple Network Management Protocol (SNMP) input packet processor of Cisco Small Business Sx200, Sx300, Sx500, ESW2 Series Managed Switches and Small Business Sx250, Sx350, Sx550 Series Switches could allow an authenticated, remote attacker to cause the SNMP application of an affected device to cease processing traffic, resulting in the CPU utilization reaching one hundred percent. Manual intervention may be required before a device resumes normal operations.
The vulnerability is due to improper validation of SNMP protocol data units (PDUs) in SNMP packets. An attacker could exploit this vulnerability by sending a malicious SNMP packet to an affected device. A successful exploit could allow the attacker to cause the device to cease forwarding traffic, which could result in a denial of service (DoS) condition.Cisco has released firmware 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-sb-snmpdos
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Vulnerable Products
This vulnerability affects the following Cisco products if they are running a vulnerable firmware release:- Small Business Sx200, Sx300, Sx500, ESW2 Series Managed Switches
- Small Business Sx250, Sx350, Sx550 Series Switches
Refer to the Cisco product release notes for the complete list of vulnerable product models: Release Notes for 200, 300, 500, and ESW2 Series Switches and Release Notes for SF250, SG250, SF350, SG350/350X/350XG, SF550X, SG550X/ 550XG, SX350X, SX550X Series Switches.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
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The device may cease to forward traffic, or the CPU utilization could spike to one hundred percent. When the device is in this state, the Out of Band (OOB) interface may still be responsive and the device could still respond to further SNMP requests. The device may need to be reloaded manually to restore service.
Contact the Cisco Technical Assistance Center (TAC) for further assistance.
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There are no workarounds that address this vulnerability.
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Cisco has released free software updates that address the vulnerability 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.htmlCustomers 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
Customers are advised to upgrade to an appropriate fixed software release as indicated in the following table:
Cisco Product First Fixed Release for This Vulnerability Small Business Sx200, Sx300, Sx500, ESW2 Series Managed Switches
1.4.10.6
Small Business Sx250, Sx350, Sx550 Series Switches
2.5.0.78
The firmware can be downloaded from the Software Center on Cisco.com by navigating to Downloads Home > Products > Switches > LAN Switches - Small Business and selecting the respective model.
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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.
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Cisco would like to thank Patrick S. Stuckenberger of August Manser AG for reporting this vulnerability.
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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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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2019-May-15
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