Cisco Security Advisory
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CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
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Multiple vulnerabilities exist in the Link Layer Discovery Protocol (LLDP) implementation for Cisco Small Business 220 Series Smart Switches. An unauthenticated, adjacent attacker could perform the following:
- Execute code on the affected device or cause it to reload unexpectedly
- Cause LLDP database corruption on the affected device
For more information about these vulnerabilities, see the Details section of this advisory.
Note: LLDP is a Layer 2 protocol. To exploit these vulnerabilities, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent).
Cisco has released firmware updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sb220-lldp-multivuls-mVRUtQ8T
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Vulnerable Products
These vulnerabilities affect Cisco Small Business 220 Series Smart Switches if they are running a vulnerable firmware release and have the LLDP feature enabled.
Note: LLDP is enabled by default on all LAN ports on Cisco Small Business 220 Series Smart Switches.
For information about which Cisco firmware 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 these vulnerabilities.
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The vulnerabilities are not dependent on one another. Exploitation of one of the vulnerabilities is not required to exploit another vulnerability. In addition, a software release that is affected by one of the vulnerabilities may not be affected by the other vulnerabilities.
Details about the vulnerabilities are as follows:
CVE-2021-34779, CVE-2021-34780:
Cisco Small Business 220 Series Smart Switches Link Layer Discovery Protocol Denial of Service VulnerabilitiesMultiple vulnerabilities in the Link Layer Discovery Protocol of Cisco Small Business 220 Series Smart Switches could allow an unauthenticated, adjacent attacker to cause an affected device to reload unexpectedly.
These vulnerabilities are due to insufficient boundary checks when processing LLDP messages. An attacker could exploit these vulnerabilities by sending a malicious LLDP packet to the targeted device. A successful exploit could allow the attacker to execute code on the affected device or cause it to reload unexpectedly, resulting in a denial of service condition.
Cisco has released firmware updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.
Bug ID(s): CSCvz29121, CSCwa32673, CSCvz29126, CSCwa32708
CVE ID: CVE-2021-34779, CVE-2021-34780
Security Impact Rating (SIR): High
CVSS Base Score: 8.8
CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVE-2021-34775, CVE-2021-34776, CVE-2021-34777, CVE-2021-34778:
Cisco Small Business 220 Series Smart Switches Link Layer Discovery Protocol Database Corruption VulnerabilitiesMultiple vulnerabilities in the Link Layer Discovery Protocol of Cisco Small Business 220 Series Smart Switches could allow an unauthenticated, adjacent attacker to cause LLDP memory corruption on an affected device.
These vulnerabilities are due to missing length validation checks when processing LLDP messages. An attacker could exploit these vulnerabilities by sending a malicious LLDP packet to the targeted device. A successful exploit could allow the attacker to cause an out-of-bounds read of the valid LLDP packet data, which could allow the attacker to cause corruption in the internal LLDP database of the affected device.
Cisco has released firmware updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.
Bug ID(s): CSCvz29108, CSCwa32785, CSCvz29116, CSCwa32762, CSCvz29120, CSCwa32793, CSCvz29134, CSCwa32782
CVE ID: CVE-2021-34775, CVE-2021-34776, CVE-2021-34777, CVE-2021-34778
Security Impact Rating (SIR): Medium
CVSS Base Score: 4.3
CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
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There are no workarounds that address these vulnerabilities. However, administrators may disable the affected feature.
To disable LLDP on the LAN interface of a device, do the following:
- Open the web-based management interface and choose Administration > Discovery LLDP > Properties.
- Uncheck the LLDP Status check box.
While this mitigation has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.
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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.htmlAdditionally, 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 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
In the following table(s), the left column lists Cisco firmware releases. The right column indicates whether a release is affected by the vulnerabilities described in this advisory and the first release that includes the fix for these vulnerabilities. Customers are advised to upgrade to an appropriate fixed firmware release as indicated in this section.
Cisco Product Cisco Firmware Release First Fixed Release Small Business 220 Series Smart Switches 1.2.1.2 and earlier 1.2.1.5 Business 220 Series Smart Switches 2.0.1.5 and earlier 2.0.1.9 To download the firmware from the Software Center on Cisco.com, click Browse all and navigate to Switches > LAN Switches - Small Business > 220 Series Smart Switches or Business 220 Series Smart Switches.
The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.
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Cisco would like to thank Qian Chen of the Codesafe Team of Legendsec at Qi'anxin Group for reporting these vulnerabilities.
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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 1.2 Added bug IDs and updated vulnerable and fixed release information. Header, Details, and Fixed Releases Final 2022-JAN-13 1.1 Updated vulnerable and fixed release information. Fixed Releases Final 2021-DEC-06 1.0 Initial public release. — Final 2021-OCT-06
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