CVE-2020-3408

Cisco IOS and IOS XE Software Split DNS Denial of Service Vulnerability

HIGH

8.6

CVSS Score

Published: September 24, 2020 at 06:01 PM UTC

Updated: June 17, 2026 at 03:18 AM UTC

129 products affected across 1 vendorIOSIOS XeAsr 1002-x

Using Cisco IOS by Cisco?

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

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

HIGH8.6

Exploit prediction

EPSS 2%

SSVC

No known exploit

Description

A vulnerability in the Split DNS feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability occurs because the regular expression (regex) engine that is used with the Split DNS feature of affected releases may time out when it processes the DNS name list configuration. An attacker could exploit this vulnerability by trying to resolve an address or hostname that the affected device handles. 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.

IOS · Cisconpm

95%

15.8(3)m3

cisco-1100-4g-integrated-services-router (environment) · cisco-1100-4gltegb-integrated-services-router (environment) · cisco-1100-4gltena-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-1100-lte-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-4221-integrated-services-router (environment) · cisco-4331-integrated-services-router (environment) · cisco-4431-integrated-services-router (environment) · cisco-4451-integrated-services-router (environment) · cisco-4461-integrated-services-router (environment) · cisco-asr-1000-x (environment) · cisco-asr-1001 (environment) · cisco-asr-1001-x (environment) · cisco-asr-1002 (environment) · cisco-asr-1002-x (environment) · cisco-asr-1004 (environment) · cisco-asr-1006 (environment) · cisco-asr-1013 (environment) · cisco-asr1001-hx (environment) · cisco-asr1001-hx-rf (environment) · cisco-asr1001-x-rf (environment) · cisco-asr1001-x-ws (environment) · cisco-asr1002-hx (environment) · cisco-asr1002-hx-rf (environment) · cisco-asr1002-hx-ws (environment) · cisco-asr1002-x-rf (environment) · cisco-asr1002-x-ws (environment) · cisco-catalyst-9800-40 (environment) · cisco-catalyst-9800-80 (environment) · cisco-catalyst-9800-cl (environment) · cisco-catalyst-9800-l (environment) · cisco-catalyst-9800-l-c (environment) · cisco-catalyst-9800-l-f (environment) · cisco-catalyst-c9200-24p (environment) · cisco-catalyst-c9200-24t (environment) · cisco-catalyst-c9200-48p (environment) · cisco-catalyst-c9200-48t (environment) · cisco-catalyst-c9200l-24p-4g (environment) · cisco-catalyst-c9200l-24p-4x (environment) · cisco-catalyst-c9200l-24pxg-2y (environment) · cisco-catalyst-c9200l-24pxg-4x (environment) · cisco-catalyst-c9200l-24t-4g (environment) · cisco-catalyst-c9200l-24t-4x (environment) · cisco-catalyst-c9200l-48p-4g (environment) · cisco-catalyst-c9200l-48p-4x (environment) · cisco-catalyst-c9200l-48pxg-2y (environment) · cisco-catalyst-c9200l-48pxg-4x (environment) · cisco-catalyst-c9200l-48t-4g (environment) · cisco-catalyst-c9200l-48t-4x (environment) · cisco-catalyst-c9300-24p (environment) · cisco-catalyst-c9300-24s (environment) · cisco-catalyst-c9300-24t (environment) · cisco-catalyst-c9300-24u (environment) · cisco-catalyst-c9300-24ux (environment) · cisco-catalyst-c9300-48p (environment) · cisco-catalyst-c9300-48s (environment) · cisco-catalyst-c9300-48t (environment) · cisco-catalyst-c9300-48u (environment) · cisco-catalyst-c9300-48un (environment) · cisco-catalyst-c9300-48uxm (environment) · cisco-catalyst-c9300l-24p-4g (environment) · cisco-catalyst-c9300l-24p-4x (environment) · cisco-catalyst-c9300l-24t-4g (environment) · cisco-catalyst-c9300l-24t-4x (environment) · cisco-catalyst-c9300l-48p-4g (environment) · cisco-catalyst-c9300l-48p-4x (environment) · cisco-catalyst-c9300l-48t-4g (environment) · cisco-catalyst-c9300l-48t-4x (environment) · cisco-catalyst-c9404r (environment) · cisco-catalyst-c9407r (environment) · cisco-catalyst-c9410r (environment) · cisco-catalyst-c9500-12q (environment) · cisco-catalyst-c9500-16x (environment) · cisco-catalyst-c9500-24q (environment) · cisco-catalyst-c9500-24y4c (environment) · cisco-catalyst-c9500-32c (environment) · cisco-catalyst-c9500-32qc (environment) · cisco-catalyst-c9500-40x (environment) · cisco-catalyst-c9500-48y4c (environment) · cisco-csr-1000v (environment) · cisco-ws-c3650-12x48uq (environment) · cisco-ws-c3650-12x48ur (environment) · cisco-ws-c3650-12x48uz (environment) · cisco-ws-c3650-24pd (environment) · cisco-ws-c3650-24pdm (environment) · cisco-ws-c3650-24ps (environment) · cisco-ws-c3650-24td (environment) · cisco-ws-c3650-24ts (environment) · cisco-ws-c3650-48fd (environment) · cisco-ws-c3650-48fq (environment) · cisco-ws-c3650-48fqm (environment) · cisco-ws-c3650-48fs (environment) · cisco-ws-c3650-48pd (environment) · cisco-ws-c3650-48pq (environment) · cisco-ws-c3650-48ps (environment) · cisco-ws-c3650-48td (environment) · cisco-ws-c3650-48tq (environment) · cisco-ws-c3650-48ts (environment) · cisco-ws-c3650-8x24uq (environment) · cisco-ws-c3850 (environment) · cisco-ws-c3850-12s (environment) · cisco-ws-c3850-12x48u (environment) · cisco-ws-c3850-12xs (environment) · cisco-ws-c3850-24p (environment) · cisco-ws-c3850-24s (environment) · cisco-ws-c3850-24t (environment) · cisco-ws-c3850-24u (environment) · cisco-ws-c3850-24xs (environment) · cisco-ws-c3850-24xu (environment) · cisco-ws-c3850-48f (environment) · cisco-ws-c3850-48p (environment) · cisco-ws-c3850-48t (environment) · cisco-ws-c3850-48u (environment) · cisco-ws-c3850-48xs (environment)

IOS Xe · Cisco

95%

15.8(3)m3

1100-4G Integrated Services Router · Ciscodevice

80%

All versions

1100-4Gltegb Integrated Services Router · Ciscodevice

80%

All versions

1100-4Gltena Integrated Services Router · Ciscodevice

80%

All versions