CVE-2020-3527: Cisco Catalyst 9200 Series Switches Jumbo Frame Denial of Service Vulnerability

Severity: high (CVSS 8.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-09-24 · updated 2026-06-17
Weakness: CWE-20

Description

A vulnerability in the Polaris kernel of Cisco Catalyst 9200 Series Switches could allow an unauthenticated, remote attacker to crash the device. The vulnerability is due to insufficient packet size validation. An attacker could exploit this vulnerability by sending jumbo frames or frames larger than the configured MTU size to the management interface of this device. A successful exploit could allow the attacker to crash the device fully before an automatic recovery.

Affected products

Cisco IOS XE: from 16.9.0 before 16.9.5; from 16.12.0 before 16.12.3 — fixed in 16.12.3, 16.9.5

How to fix

Upgrade to a fixed version: Cisco IOS XE 16.12.3, 16.9.5. Check the vendor advisory for mitigations.

References

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