CVE-2021-1621

Cisco IOS XE Software Interface Queue Wedge Denial of Service Vulnerability

HIGH

7.4

CVSS Score

Published: September 23, 2021 at 02:31 AM UTC

Updated: June 17, 2026 at 03:32 AM UTC

45 products affected across 1 vendorIOS XeAsr 1002-xAsr 1006

Using Cisco IOS XE Software by Cisco?

Get instant alerts when new vulnerabilities affect Cisco IOS XE Software - before attackers find them.

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

HIGH7.4

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

Description

A vulnerability in the Layer 2 punt code of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a queue wedge on an interface that receives specific Layer 2 frames, resulting in a denial of service (DoS) condition. This vulnerability is due to improper handling of certain Layer 2 frames. An attacker could exploit this vulnerability by sending specific Layer 2 frames on the segment the router is connected to. A successful exploit could allow the attacker to cause a queue wedge on the interface, resulting in a DoS condition.

Affected

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

IOS Xe · Cisco

95%

v < 17.3.1

Affected range stops below 17.3.1, so it looks safe — our inference, not a vendor statement

cisco-1000-integrated-services-router (environment) · cisco-1100-4g-6g-integrated-services-router (environment) · cisco-1100-4p-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-1160-integrated-services-router (environment) · cisco-4000-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-integrated-services-router (environment) · cisco-4451-x-integrated-services-router (environment) · cisco-4461-integrated-services-router (environment) · cisco-asr-1000 (environment) · cisco-asr-1000-x (environment) · cisco-asr-1001 (environment) · cisco-asr-1001-hx (environment) · cisco-asr-1001-hx-r (environment) · cisco-asr-1001-x (environment) · cisco-asr-1001-x-r (environment) · cisco-asr-1002 (environment) · cisco-asr-1002-hx (environment) · cisco-asr-1002-hx-r (environment) · cisco-asr-1002-x (environment) · cisco-asr-1002-x-r (environment) · cisco-asr-1004 (environment) · cisco-asr-1006 (environment) · cisco-asr-1006-x (environment) · cisco-asr-1009-x (environment) · cisco-asr-1013 (environment) · cisco-asr-1023 (environment) · cisco-csr-1000v (environment) · cisco-isrv (environment)

1000 Integrated Services Router · Ciscodevice

80%

All versions

1100-4G/6G Integrated Services Router · Ciscodevice

80%

All versions

1100-4P Integrated Services Router · Ciscodevice

80%

All versions

1100-8P Integrated Services Router · Ciscodevice

80%

All versions