CVE-2023-20027

Cisco IOS XE Software Virtual Fragmentation Reassembly Denial of Service Vulnerability

HIGH
8.6
CVSS Score
Published: March 23, 2023 at 12:00 AM UTC
Updated: June 17, 2026 at 05:29 AM UTC
35 products affected across 1 vendorIOS Xe4331 Integrated Services Router4431 Integrated Services Router

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Severity
HIGH8.6
Exploit prediction
EPSS 1.0%
SSVC
No known exploit

Description

A vulnerability in the implementation of the IPv4 Virtual Fragmentation Reassembly (VFR) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper reassembly of large packets that occurs when VFR is enabled on either a tunnel interface or on a physical interface that is configured with a maximum transmission unit (MTU) greater than 4,615 bytes. An attacker could exploit this vulnerability by sending fragmented packets through a VFR-enabled interface on an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

cisco-1000-integrated-services-router (environment) · cisco-1100-4g-6g-integrated-services-router (environment) · cisco-1100-4g-integrated-services-router (environment) · cisco-1100-4p-integrated-services-router (environment) · cisco-1100-6g-integrated-services-router (environment) · cisco-1100-8p-integrated-services-router (environment) · cisco-1100-integrated-services-router (environment) · cisco-1101-4p-integrated-services-router (environment) · cisco-1101-integrated-services-router (environment) · cisco-1109-2p-integrated-services-router (environment) · cisco-1109-4p-integrated-services-router (environment) · cisco-1109-integrated-services-router (environment) · cisco-1111x-8p-integrated-services-router (environment) · cisco-1111x-integrated-services-router (environment) · cisco-111x-integrated-services-router (environment) · cisco-1120-integrated-services-router (environment) · cisco-1131-integrated-services-router (environment) · cisco-1160-integrated-services-router (environment) · cisco-4221-integrated-services-router (environment) · cisco-4321-integrated-services-router (environment) · cisco-4331-integrated-services-router (environment) · cisco-4351-integrated-services-router (environment) · cisco-4431-integrated-services-router (environment) · cisco-4451-x-integrated-services-router (environment) · cisco-4461-integrated-services-router (environment) · cisco-c8200-1n-4t (environment) · cisco-c8200l-1n-4t (environment) · cisco-c8500l-8s4x (environment) · cisco-catalyst-8000v-edge (environment) · cisco-catalyst-8300-1n1s-4t2x (environment) · cisco-catalyst-8300-1n1s-6t (environment) · cisco-catalyst-8300-2n2s-4t2x (environment) · cisco-catalyst-8300-2n2s-6t (environment) · cisco-cloud-services-router-1000v (environment)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.6HIGHcisco
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-416NVD-CWE-noinfo

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