CVE-2026-20124: Cisco IOS XE

High severity, CVSS 7.7. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Cisco IOS XE: version 3.13.9s only; version 3.13.10s only; version 3.16.6bs only; version 3.16.7as only; version 3.16.7bs only; version 3.16.7s only; …

Published 2026-08-05. Last modified 2026-09-17.