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Cisco Nexus 9000 Series Fabric Switches in ACI Mode SNMP Denial of Service Vulnerability

cisco-sa-nxos-dsnmp-cNN39Uh · High · Published · Updated

A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco Nexus 9000 Series Fabric Switches in ACI mode could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper processing when parsing SNMP requests. An attacker could exploit this vulnerability by continuously sending SNMP queries to a specific MIB of an affected device. A successful exploit could allow the attacker to cause a kernel panic on the device, resulting in a reload and a DoS condition. Note: This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMPv1 or SNMPv2c, the attacker must have a valid read-only SNMP community string for the affected system. To exploit this vulnerability through SNMPv3, the attacker must have valid SNMP user credentials for the affected system. Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-dsnmp-cNN39Uh This advisory is part of the February 2026 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: February 2026 Semiannual Cisco FXOS and NX-OS Software Security Advisory Bundled Publication.

Cisco advisory ·CSAF JSON

Workarounds

A workaround for this vulnerability exists for AAA providers that are configured with IPv4 DNS names. Update all AAA providers from a DNS name (hostname or FQDN) to an IPv4 address configuration. For more information about AAA configuration, see Cisco Application Centric Infrastructure Fundamentals, Release 6.1(x) https://www.cisco.com/c/en/us/td/docs/dcn/aci/apic/6x/aci-fundamentals/cisco-aci-fundamentals-61x/aaa-60x.html?bookSearch=true .

There is no workaround for IPv6 configurations.

While this workaround has been deployed and 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.

CVEsCVE-2026-20048
Cisco Bug IDsCSCwq57598
CVSS ScoreBase 7.7
Base 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
Product Names From Source
Cisco NX-OS System Software in ACI Mode 15.2(1g), Cisco NX-OS System Software in ACI Mode 15.2(2e), Cisco NX-OS System Software in ACI Mode 15.2(2f), Cisco NX-OS System Software in ACI Mode 15.2(2g), Cisco NX-OS System Software in ACI Mode 15.2(2h), Cisco NX-OS System Software in ACI Mode 15.2(3e), Cisco NX-OS System Software in ACI Mode 15.2(3f), Cisco NX-OS System Software in ACI Mode 15.2(3g), Cisco NX-OS System Software in ACI Mode 15.2(4d), Cisco NX-OS System Software in ACI Mode 15.2(4e), Cisco NX-OS System Software in ACI Mode 15.2(5c), Cisco NX-OS System Software in ACI Mode 15.2(5d), Cisco NX-OS System Software in ACI Mode 15.2(5e), Cisco NX-OS System Software in ACI Mode 15.2(4f), Cisco NX-OS System Software in ACI Mode 15.2(6e), Cisco NX-OS System Software in ACI Mode 15.2(6g), Cisco NX-OS System Software in ACI Mode 15.2(7f), Cisco NX-OS System Software in ACI Mode 15.2(7g), Cisco NX-OS System Software in ACI Mode 15.2(6h), Cisco NX-OS System Software in ACI Mode 15.2(8d), Cisco NX-OS System Software in ACI Mode 15.2(8e), Cisco NX-OS System Software in ACI Mode 15.2(8f), Cisco NX-OS System Software in ACI Mode 15.2(8g), Cisco NX-OS System Software in ACI Mode 15.2(8h), Cisco NX-OS System Software in ACI Mode 15.2(8i), Cisco NX-OS System Software in ACI Mode 16.0(1g), Cisco NX-OS System Software in ACI Mode 16.0(1j), Cisco NX-OS System Software in ACI Mode 16.0(2h), Cisco NX-OS System Software in ACI Mode 16.0(2j), Cisco NX-OS System Software in ACI Mode 16.0(3d), Cisco NX-OS System Software in ACI Mode 16.0(3e), Cisco NX-OS System Software in ACI Mode 16.0(4c), Cisco NX-OS System Software in ACI Mode 16.0(5h), Cisco NX-OS System Software in ACI Mode 16.0(3g), Cisco NX-OS System Software in ACI Mode 16.0(5j), Cisco NX-OS System Software in ACI Mode 16.0(6c), Cisco NX-OS System Software in ACI Mode 16.0(7e), Cisco NX-OS System Software in ACI Mode 16.0(8e), Cisco NX-OS System Software in ACI Mode 16.0(8f), Cisco NX-OS System Software in ACI Mode 16.0(9c), Cisco NX-OS System Software in ACI Mode 16.0(9d), Cisco NX-OS System Software in ACI Mode 16.0(6h), Cisco NX-OS System Software in ACI Mode 16.0(8h), Cisco NX-OS System Software in ACI Mode 16.0(9e), Cisco NX-OS System Software in ACI Mode 15.3(1d), Cisco NX-OS System Software in ACI Mode 15.3(2a), Cisco NX-OS System Software in ACI Mode 15.3(2b), Cisco NX-OS System Software in ACI Mode 15.3(2c), Cisco NX-OS System Software in ACI Mode 15.3(2d), Cisco NX-OS System Software in ACI Mode 15.3(2e), Cisco NX-OS System Software in ACI Mode 15.3(2f), Cisco NX-OS System Software in ACI Mode 16.1(1f), Cisco NX-OS System Software in ACI Mode 16.1(2f), Cisco NX-OS System Software in ACI Mode 16.1(2g), Cisco NX-OS System Software in ACI Mode 16.1(3f), Cisco NX-OS System Software in ACI Mode 16.1(3g), Cisco NX-OS System Software in ACI Mode 16.1(4h), Cisco NX-OS System Software in ACI Mode, Cisco Nexus 9000 Series Switches

Related Products

Product CVE Evidence
Cisco Firepower Extensible Operating System (FXOS) CVE-2026-20048 Cisco OpenVuln
Cisco NX-OS Software CVE-2026-20048 Cisco OpenVuln
Cisco NX-OS System Software in ACI Mode CVE-2026-20048 Cisco OpenVuln
Cisco Nexus 9000 Series Switches CVE-2026-20048 Cisco OpenVuln