High [CVE-2026-20124] Cisco IOS XE Software SNMP Denial of Service Vulnerability
This high-severity Cisco advisory covers CVE-2026-20124 affecting IOS XE Software.
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Summary
A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software could allow an authenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition.
This vulnerability is due to improper error handling when parsing SNMP requests. This vulnerability affects all versions of SNMP — Versions 1, 2c, and 3.
An attacker could exploit this vulnerability by sending a malformed SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly.
The attacker must have the SNMPv1 or v2c read-only or read-write community string or valid SNMPv3 user credentials on the affected device.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
There is a mitigation that addresses this vulnerability.
- Scope: This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco IOS XE Software and have SNMP enabled.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation checklist
- There are no workarounds that address this vulnerability.
- However, there is a mitigation. Administrators can disable the affected OIDs on a device. Not all software will support the OID that is listed in the mitigation. If the OID is not valid for specific software, then it is not affected by this vulnerability. Excluding these OIDs may affect device management through SNMP, such as discovery and hardware inventory.
- To create or update a view entry and disable the affected OIDs, use the snmp-server view global configuration command, as shown in the following example:
- !Standard VIEW and Security Exclusions
- snmp-server view NO_BAD_SNMP iso included
- snmp-server view NO_BAD_SNMP snmpUsmMIB excluded
- snmp-server view NO_BAD_SNMP snmpVacmMIB excluded
- snmp-server view NO_BAD_SNMP snmpCommunityMIB excluded
- !End Standard View
- !Advisory Specific Mappings
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
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